Plants

19 pages, 2832 KiB

Open AccessEditor’s ChoiceArticle

UV-B Physiological Changes Under Conditions of Distress and Eustress in Sweet Basil

by Haana Mosadegh, Alice Trivellini, Mariella Lucchesini, Antonio Ferrante, Rita Maggini, Paolo Vernieri and Anna Mensuali Sodi

Plants 2019, 8(10), 396; https://doi.org/10.3390/plants8100396 - 4 Oct 2019

Cited by 35 | Viewed by 5779

Abstract

UV-B radiation has been previously reported to induce protective or deleterious effects on plants depending on the UV-B irradiation doses. To elucidate how these contrasting events are physiologically coordinated, we exposed sweet basil plants to two UV-B doses: low (8.5 kJ m⁻² [...] Read more.

UV-B radiation has been previously reported to induce protective or deleterious effects on plants depending on the UV-B irradiation doses. To elucidate how these contrasting events are physiologically coordinated, we exposed sweet basil plants to two UV-B doses: low (8.5 kJ m⁻² day⁻¹, 30 min exposure) and high (68 kJ m⁻² day⁻¹, 4 h exposure), with the plants given both doses once continuously in a single day. Physiological tests during and after both UV-B exposures were performed by comparing the stress-induced damage and adverse effects on photosynthetic activity, the concentration and composition of photosynthetic and non-photosynthetic pigments, and stress-related hormones biosynthesis in basil plants. Our results showed that upon receiving a high UV-B dose, a severe inactivation of oxygen evolving complex (OEC) activity at the PSII donor side and irreversible PSII photodamage caused primarily by limitation of the acceptor side occurred, which overloaded protective mechanisms and finally led to the death of the plants. In contrast, low UV-B levels did not induce any signs of UV-B stress injuries. The OEC partial limitation and the inactivation of the electron transport chain allowed the activation of photoprotective mechanisms, avoiding irreversible damage to PSII. Overall results indicate the importance of a specific response mechanisms regulating photoprotection vs irreversible photoinhibition in basil that were modulated depending on the UV-B doses. Full article

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20 pages, 8079 KiB

Open AccessEditor’s ChoiceArticle

Magnesium-Deficiency Effects on Pigments, Photosynthesis and Photosynthetic Electron Transport of Leaves, and Nutrients of Leaf Blades and Veins in Citrus sinensis Seedlings

by Xin Ye, Xu-Feng Chen, Chong-Ling Deng, Lin-Tong Yang, Ning-Wei Lai, Jiu-Xin Guo and Li-Song Chen

Plants 2019, 8(10), 389; https://doi.org/10.3390/plants8100389 - 30 Sep 2019

Cited by 60 | Viewed by 8257

Abstract

Citrus sinensis seedlings were irrigated with nutrient solution at a concentration of 0 (Mg-deficiency) or 2 (Mg-sufficiency) mM Mg (NO₃)₂ for 16 weeks. Mg-deficiency-induced interveinal chlorosis, vein enlargement and corkiness, and alterations of gas exchange, pigments, chlorophyll a fluorescence (OJIP) [...] Read more.

Citrus sinensis seedlings were irrigated with nutrient solution at a concentration of 0 (Mg-deficiency) or 2 (Mg-sufficiency) mM Mg (NO₃)₂ for 16 weeks. Mg-deficiency-induced interveinal chlorosis, vein enlargement and corkiness, and alterations of gas exchange, pigments, chlorophyll a fluorescence (OJIP) transients and related parameters were observed in middle and lower leaves, especially in the latter, but not in upper leaves. Mg-deficiency might impair the whole photosynthetic electron transport, including structural damage to thylakoids, ungrouping of photosystem II (PSII), inactivation of oxygen-evolving complex (OEC) and reaction centers (RCs), increased reduction of primary quinone electron acceptor (Q_A) and plastoquinone pool at PSII acceptor side and oxidation of PSI end-electron acceptors, thus lowering energy transfer and absorption efficiency and the transfer of electrons to the dark reactions, hence, the rate of CO₂ assimilation in Mg-deficiency middle and lower leaves. Although potassium, Mg, manganese and zinc concentration in blades displayed a significant and positive relationship with the corresponding element concentration in veins, respectively, great differences existed in Mg-deficiency-induced alterations of nutrient concentrations between leaf blades and veins. For example, Mg-deficiency increased boron level in the blades of upper leaves, decreased boron level in the blades of lower leaves, but did not affect boron level in the blades of middle leaves and veins of upper, middle and lower leaves. To conclude, Mg-deficiency-induced interveinal chlorosis, vein enlargement, and corkiness, and alterations to photosynthesis and related parameters increased with increasing leaf age. Mg-deficiency-induced enlargement and corkiness of veins were not caused by Mg-deficiency-induced boron-starvation. Full article

(This article belongs to the Special Issue Advances in Citrus Research)

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19 pages, 524 KiB

Open AccessEditor’s ChoiceArticle

Antimicrobial Activity, Antioxidant Potential, Cytotoxicity and Phytochemical Profiling of Four Plants Locally Used against Skin Diseases

by John A. Asong, Stephen O. Amoo, Lyndy J. McGaw, Sanah M. Nkadimeng, Adeyemi O. Aremu and Wilfred Otang-Mbeng

Plants 2019, 8(9), 350; https://doi.org/10.3390/plants8090350 - 15 Sep 2019

Cited by 38 | Viewed by 6248

Abstract

Although orthodox medications are available for skin diseases, expensive dermatological services have necessitated the use of medicinal plants as a cheaper alternative. This study evaluated the pharmacological and phytochemical profiles of four medicinal plants (Drimia sanguinea, Elephantorrhiza elephantina, Helichrysum paronychioides [...] Read more.

Although orthodox medications are available for skin diseases, expensive dermatological services have necessitated the use of medicinal plants as a cheaper alternative. This study evaluated the pharmacological and phytochemical profiles of four medicinal plants (Drimia sanguinea, Elephantorrhiza elephantina, Helichrysum paronychioides, and Senecio longiflorus) used for treating skin diseases. Petroleum ether and 50% methanol extracts of the plants were screened for antimicrobial activity against six microbes: Bacillus cereus, Shigella flexneri, Candida glabrata, Candida krusei, Trichophyton rubrum and Trichophyton tonsurans using the micro-dilution technique. Antioxidant activity was conducted using 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging and β-carotene linoleic acid models. Cytotoxicity was determined against African green monkey Vero kidney cells based on the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Spectrophotometric and Gas Chromatography-Mass Spectrometry (GC-MS) methods were used to evaluate the phytochemical constituents. All the extracts demonstrated varying degrees of antimicrobial potencies. Shigella flexneri, Candida glabrata, Trichophyton rubrum and Trichophyton tonsurans were most susceptible at 0.10 mg/mL. In the DPPH test, EC₅₀ values ranged from approximately 6–93 µg/mL and 65%–85% antioxidant activity in the β-carotene linoleic acid antioxidant activity model. The phenolic and flavonoid contents ranged from 3.5–64 mg GAE/g and 1.25–28 mg CE/g DW, respectively. The LC₅₀ values of the cytotoxicity assay ranged from 0.015–5622 µg/mL. GC-MS analysis revealed a rich pool (94–198) of bioactive compounds including dotriacontane, benzothiazole, heptacosane, bumetrizole, phthalic acid, stigmasterol, hexanoic acid and eicosanoic acid, which were common to the four plants. The current findings provide some degree of scientific evidence supporting the use of these four plants in folk medicine. However, the plants with high cytotoxicity need to be used with caution. Full article

(This article belongs to the Section Phytochemistry)

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19 pages, 3580 KiB

Open AccessEditor’s ChoiceArticle

Understanding the Role of the Antioxidant System and the Tetrapyrrole Cycle in Iron Deficiency Chlorosis

by Carla S. Santos, Rengin Ozgur, Baris Uzilday, Ismail Turkan, Mariana Roriz, António O.S.S. Rangel, Susana M.P. Carvalho and Marta W. Vasconcelos

Plants 2019, 8(9), 348; https://doi.org/10.3390/plants8090348 - 13 Sep 2019

Cited by 46 | Viewed by 5374

Abstract

Iron deficiency chlorosis (IDC) is an abiotic stress often experienced by soybean, owing to the low solubility of iron in alkaline soils. Here, soybean lines with contrasting Fe efficiencies were analyzed to test the hypothesis that the Fe efficiency trait is linked to [...] Read more.

Iron deficiency chlorosis (IDC) is an abiotic stress often experienced by soybean, owing to the low solubility of iron in alkaline soils. Here, soybean lines with contrasting Fe efficiencies were analyzed to test the hypothesis that the Fe efficiency trait is linked to antioxidative stress signaling via proper management of tissue Fe accumulation and transport, which in turn influences the regulation of heme and non heme containing enzymes involved in Fe uptake and ROS scavenging. Inefficient plants displayed higher oxidative stress and lower ferric reductase activity, whereas root and leaf catalase activity were nine-fold and three-fold higher, respectively. Efficient plants do not activate their antioxidant system because there is no formation of ROS under iron deficiency; while inefficient plants are not able to deal with ROS produced under iron deficiency because ascorbate peroxidase and superoxide dismutase are not activated because of the lack of iron as a cofactor, and of heme as a constituent of those enzymes. Superoxide dismutase and peroxidase isoenzymatic regulation may play a determinant role: 10 superoxide dismutase isoenzymes were observed in both cultivars, but iron superoxide dismutase activity was only detected in efficient plants; 15 peroxidase isoenzymes were observed in the roots and trifoliate leaves of efficient and inefficient cultivars and peroxidase activity levels were only increased in roots of efficient plants. Full article

(This article belongs to the Special Issue ROS Responses in Plants)

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18 pages, 3943 KiB

Open AccessEditor’s ChoiceReview

Current Status and Future Prospects in Herbicide Discovery

by Franck E. Dayan

Plants 2019, 8(9), 341; https://doi.org/10.3390/plants8090341 - 11 Sep 2019

Cited by 162 | Viewed by 17995

Abstract

Herbicides represent about 60% of the pesticides (by volume) used worldwide. The success of herbicides can be attributed in part to a relatively steady discovery of one unique mechanisms of action (MOA) every two years from the early 1950s to the mid-1980s. While [...] Read more.

Herbicides represent about 60% of the pesticides (by volume) used worldwide. The success of herbicides can be attributed in part to a relatively steady discovery of one unique mechanisms of action (MOA) every two years from the early 1950s to the mid-1980s. While this situation changed dramatically after the introduction of glyphosate-resistant crops, evolution of resistance to glyphosate has renewed the agrichemical industry interest in new chemistry interacting with novel target sites. This review analyses recent characterization of new herbicide target sites, the chemical classes developed to inhibit these target sites, and where appropriate the innovative technologies used in these discovery programs. Full article

(This article belongs to the Special Issue Herbicide Resistance in Plants)

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9 pages, 2279 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Herbicide Resistance Traits in Maize and Soybean: Current Status and Future Outlook

by Vijay K. Nandula

Plants 2019, 8(9), 337; https://doi.org/10.3390/plants8090337 - 9 Sep 2019

Cited by 54 | Viewed by 8379

Abstract

This article reviews, focusing on maize and soybean, previous efforts to develop nontransgenic herbicide-resistant crops (HRCs), currently available transgenic HRC traits and technologies, as well as future chemical weed management options over the horizon. Since the mid twentieth century, herbicides rapidly replaced all [...] Read more.

This article reviews, focusing on maize and soybean, previous efforts to develop nontransgenic herbicide-resistant crops (HRCs), currently available transgenic HRC traits and technologies, as well as future chemical weed management options over the horizon. Since the mid twentieth century, herbicides rapidly replaced all other means of weed management. Overreliance on ‘herbicide-only’ weed control strategies hastened evolution of HR weed species. Glyphosate-resistant (GR) crop technology revolutionized weed management in agronomic crops, but GR weeds, led by Palmer amaranth, severely reduced returns from various cropping systems and affected the bottom line of growers across the world. An additional problem was the lack of commercialization of a new herbicide mode of action since the 1990s. Auxinic HRCs offer a short-term alternative for management of GR Palmer amaranth and other weed species. New HRCs stacked with multiple herbicide resistance traits and at least two new herbicide modes of action expected to be available in the mid-2020s provide new chemical options for weed management in row crops in the next decade. Full article

(This article belongs to the Special Issue Herbicide Resistance in Plants)

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19 pages, 1835 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Jasmonates—the Master Regulator of Rice Development, Adaptation and Defense

by Hieu Trang Nguyen, Huong Thi Mai To, Michel Lebrun, Stephane Bellafiore and Antony Champion

Plants 2019, 8(9), 339; https://doi.org/10.3390/plants8090339 - 9 Sep 2019

Cited by 43 | Viewed by 7778

Abstract

Rice is one of the most important food crops worldwide, as well as the model plant in molecular studies on the cereals group. Many different biotic and abiotic agents often limit rice production and threaten food security. Understanding the molecular mechanism, by which [...] Read more.

Rice is one of the most important food crops worldwide, as well as the model plant in molecular studies on the cereals group. Many different biotic and abiotic agents often limit rice production and threaten food security. Understanding the molecular mechanism, by which the rice plant reacts and resists these constraints, is the key to improving rice production to meet the demand of an increasing population. The phytohormone jasmonic acid (JA) and related compounds, collectively called jasmonates, are key regulators in plant growth and development. They are also one of the central players in plant immunity against biotic attacks and adaptation to unfavorable environmental conditions. Here, we review the most recent knowledge about jasmonates signaling in the rice crop model. We highlight the functions of jasmonates signaling in many adaptive responses, and also in rice growth and development processes. We also draw special attention to different signaling modules that are controlled by jasmonates in rice. Full article

(This article belongs to the Special Issue The Jasmonate Pathway: New Actors, Mechanisms and Impacts)

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18 pages, 676 KiB

Open AccessEditor’s ChoiceReview

Regulation of Symbiotic Nitrogen Fixation in Legume Root Nodules

by Andrés R. Schwember, Joachim Schulze, Alejandro del Pozo and Ricardo A. Cabeza

Plants 2019, 8(9), 333; https://doi.org/10.3390/plants8090333 - 6 Sep 2019

Cited by 68 | Viewed by 14449

Abstract

In most legume nodules, the di-nitrogen (N₂)-fixing rhizobia are present as organelle-like structures inside their root host cells. Many processes operate and interact within the symbiotic relationship between plants and nodules, including nitrogen (N)/carbon (C) metabolisms, oxygen flow through nodules, oxidative [...] Read more.

In most legume nodules, the di-nitrogen (N₂)-fixing rhizobia are present as organelle-like structures inside their root host cells. Many processes operate and interact within the symbiotic relationship between plants and nodules, including nitrogen (N)/carbon (C) metabolisms, oxygen flow through nodules, oxidative stress, and phosphorous (P) levels. These processes, which influence the regulation of N₂ fixation and are finely tuned on a whole-plant basis, are extensively reviewed in this paper. The carbonic anhydrase (CA)-phosphoenolpyruvate carboxylase (PEPC)-malate dehydrogenase (MDH) is a key pathway inside nodules involved in this regulation, and malate seems to play a crucial role in many aspects of symbiotic N₂ fixation control. How legumes specifically sense N-status and how this stimulates all of the regulatory factors are key issues for understanding N₂ fixation regulation on a whole-plant basis. This must be thoroughly studied in the future since there is no unifying theory that explains all of the aspects involved in regulating N₂ fixation rates to date. Finally, high-throughput functional genomics and molecular tools (i.e., miRNAs) are currently very valuable for the identification of many regulatory elements that are good candidates for accurately dissecting the particular N₂ fixation control mechanisms associated with physiological responses to abiotic stresses. In combination with existing information, utilizing these abundant genetic molecular tools will enable us to identify the specific mechanisms underlying the regulation of N₂ fixation. Full article

(This article belongs to the Special Issue Nitrogen-Fixing Plants )

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11 pages, 692 KiB

Open AccessEditor’s ChoiceReview

A Review of Plant Vacuoles: Formation, Located Proteins, and Functions

by Xiaona Tan, Kaixia Li, Zheng Wang, Keming Zhu, Xiaoli Tan and Jun Cao

Plants 2019, 8(9), 327; https://doi.org/10.3390/plants8090327 - 5 Sep 2019

Cited by 61 | Viewed by 11246

Abstract

Vacuoles, cellular membrane-bound organelles, are the largest compartments of cells, occupying up to 90% of the volume of plant cells. Vacuoles are formed by the biosynthetic and endocytotic pathways. In plants, the vacuole is crucial for growth and development and has a variety [...] Read more.

Vacuoles, cellular membrane-bound organelles, are the largest compartments of cells, occupying up to 90% of the volume of plant cells. Vacuoles are formed by the biosynthetic and endocytotic pathways. In plants, the vacuole is crucial for growth and development and has a variety of functions, including storage and transport, intracellular environmental stability, and response to injury. Depending on the cell type and growth conditions, the size of vacuoles is highly dynamic. Different types of cell vacuoles store different substances, such as alkaloids, protein enzymes, inorganic salts, sugars, etc., and play important roles in multiple signaling pathways. Here, we summarize vacuole formation, types, vacuole-located proteins, and functions. Full article

(This article belongs to the Section Plant Physiology and Metabolism)

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18 pages, 622 KiB

Open AccessEditor’s ChoiceArticle

SNP and Haplotype-Based Genomic Selection of Quantitative Traits in Eucalyptus globulus

by Paulina Ballesta, Carlos Maldonado, Paulino Pérez-Rodríguez and Freddy Mora

Plants 2019, 8(9), 331; https://doi.org/10.3390/plants8090331 - 5 Sep 2019

Cited by 32 | Viewed by 5818

Abstract

Eucalyptus globulus (Labill.) is one of the most important cultivated eucalypts in temperate and subtropical regions and has been successfully subjected to intensive breeding. In this study, Bayesian genomic models that include the effects of haplotype and single nucleotide polymorphisms (SNP) were assessed [...] Read more.

Eucalyptus globulus (Labill.) is one of the most important cultivated eucalypts in temperate and subtropical regions and has been successfully subjected to intensive breeding. In this study, Bayesian genomic models that include the effects of haplotype and single nucleotide polymorphisms (SNP) were assessed to predict quantitative traits related to wood quality and tree growth in a 6-year-old breeding population. To this end, the following markers were considered: (a) ~14 K SNP markers (SNP), (b) ~3 K haplotypes (HAP), and (c) haplotypes and SNPs that were not assigned to a haplotype (HAP-SNP). Predictive ability values (PA) were dependent on the genomic prediction models and markers. On average, Bayesian ridge regression (BRR) and Bayes C had the highest PA for the majority of traits. Notably, genomic models that included the haplotype effect (either HAP or HAP-SNP) significantly increased the PA of low-heritability traits. For instance, BRR based on HAP had the highest PA (0.58) for stem straightness. Consistently, the heritability estimates from genomic models were higher than the pedigree-based estimates for these traits. The results provide additional perspectives for the implementation of genomic selection in Eucalyptus breeding programs, which could be especially beneficial for improving traits with low heritability. Full article

(This article belongs to the Special Issue Genomics for Plant Breeding)

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15 pages, 2158 KiB

Open AccessEditor’s ChoiceArticle

Early Season Drought Largely Reduces Grain Yield in Wheat Cultivars with Smaller Root Systems

by Victoria Figueroa-Bustos, Jairo A. Palta, Yinglong Chen and Kadambot H.M. Siddique

Plants 2019, 8(9), 305; https://doi.org/10.3390/plants8090305 - 27 Aug 2019

Cited by 30 | Viewed by 3989

Abstract

In the Australian grainbelt, early winter rainfall has declined during the last 30 years, and farmers sow their crops dry, increasing the risk of early season drought. This study aimed to examine whether differences in the root systems were associated with tolerance to [...] Read more.

In the Australian grainbelt, early winter rainfall has declined during the last 30 years, and farmers sow their crops dry, increasing the risk of early season drought. This study aimed to examine whether differences in the root systems were associated with tolerance to early season drought. Three wheat cultivars with different root systems were grown in 1 m columns in a glasshouse. Immediately after sowing in dry soil, 440 mL water (equivalent to 25 mm rainfall) was supplied to each column, and no water was added to induce the early-season drought for the next 30 days. Shoot and root traits were measured at the end of the early season drought, anthesis and at maturity, respectively. The restricted water supply reduced Ψ_leaf, stomatal conductance, leaf photosynthetic rate, shoot and root biomass. Early season drought delayed phenology in all cultivars, but there was recovery of root and shoot biomass at anthesis in all three cultivars. Leaf area and shoot biomass at anthesis in Bahatans-87 (large root system) recovered better than Tincurrin (small root system). At maturity, early season drought reduced grain yield more in Tincurrin than Bahatans-87. The slow phenology of Bahatans-87 allowed greater recovery after the drought in leaf area and shoot biomass, which may explain the smaller reduction in grain yield after early season drought. Full article

(This article belongs to the Special Issue Root System Structure and Function: A Themed Issue in Honor of Professor Yoav Waisel)

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22 pages, 2297 KiB

Open AccessEditor’s ChoiceArticle

GWAS for Starch-Related Parameters in Japonica Rice (Oryza sativa L.)

by Chiara Biselli, Andrea Volante, Francesca Desiderio, Alessandro Tondelli, Alberto Gianinetti, Franca Finocchiaro, Federica Taddei, Laura Gazza, Daniela Sgrulletta, Luigi Cattivelli and Giampiero Valè

Plants 2019, 8(8), 292; https://doi.org/10.3390/plants8080292 - 19 Aug 2019

Cited by 30 | Viewed by 6784

Abstract

Rice quality is mainly related to the following two starch components, apparent amylose content (AAC) and resistant starch (RS). The former affects grain cooking properties, while RS acts as a prebiotic. In the present study, a Genome Wide Association Scan (GWAS) was performed [...] Read more.

Rice quality is mainly related to the following two starch components, apparent amylose content (AAC) and resistant starch (RS). The former affects grain cooking properties, while RS acts as a prebiotic. In the present study, a Genome Wide Association Scan (GWAS) was performed using 115 rice japonica accessions, including tropical and temperate genotypes, with the purpose of expanding the knowledge of the genetic bases affecting RS and AAC. High phenotypic variation was recorded for the two traits, which positively correlated. Moreover, both the parameters correlated with seed length (positive correlation) and seed width (negative correlation). A correlational selection according to human preferences has been hypothesized for the two starch traits and grain size. In addition, human selection has been proposed as the causal agent even for the different phenotypes related to starch and grain size showed by the tropical and temperate japonica accessions utilized in this study. The present GWAS led to the identification of 11 associations for RS on seven chromosomes and five associations for AAC on chromosome 6. Candidate genes and co-positional relationships with quantitative trait loci (QTLs) previously identified as affecting RS and AAC were identified for 6 associations. The candidate genes and the new RS- and/or AAC-associated regions detected provide valuable sources for future functional characterizations and for breeding programs aimed at improving rice grain quality. Full article

(This article belongs to the Special Issue Cereal Breeding: Improving Seed Vigour Traits and Grain Quality)

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12 pages, 1399 KiB

Open AccessEditor’s ChoiceArticle

Transient Heat Waves May Affect the Photosynthetic Capacity of Susceptible Wheat Genotypes Due to Insufficient Photosystem I Photoprotection

by Erik Chovancek, Marek Zivcak, Lenka Botyanszka, Pavol Hauptvogel, Xinghong Yang, Svetlana Misheva, Sajad Hussain and Marian Brestic

Plants 2019, 8(8), 282; https://doi.org/10.3390/plants8080282 - 12 Aug 2019

Cited by 51 | Viewed by 4745

Abstract

We assessed the photosynthetic responses of eight wheat varieties in conditions of a simulated heat wave in a transparent plastic tunnel for one week. We found that high temperatures (up to 38 °C at midday and above 20 °C at night) had a [...] Read more.

We assessed the photosynthetic responses of eight wheat varieties in conditions of a simulated heat wave in a transparent plastic tunnel for one week. We found that high temperatures (up to 38 °C at midday and above 20 °C at night) had a negative effect on the photosynthetic functions of the plants and provided differentiation of genotypes through sensitivity to heat. Measurements of gas exchange showed that the simulated heat wave led to a 40% decrease in photosynthetic activity on average in comparison to the control, with an unequal recovery of individual genotypes after a release from stress. Our results indicate that the ability to recover after heat stress was associated with an efficient regulation of linear electron transport and the prevention of over-reduction in the acceptor side of photosystem I. Full article

(This article belongs to the Special Issue Molecular Mechanisms and Genetics of Plant Resistance to Abiotic Stress)

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12 pages, 2694 KiB

Open AccessEditor’s ChoiceArticle

Comparative and Phylogenetic Analyses of Ginger (Zingiber officinale) in the Family Zingiberaceae Based on the Complete Chloroplast Genome

by Yingxian Cui, Liping Nie, Wei Sun, Zhichao Xu, Yu Wang, Jing Yu, Jingyuan Song and Hui Yao

Plants 2019, 8(8), 283; https://doi.org/10.3390/plants8080283 - 12 Aug 2019

Cited by 54 | Viewed by 7152

Abstract

Zingiber officinale, commonly known as ginger, is an important plant of the family Zingiberaceae and is widely used as an herbal medicine and condiment. The lack of chloroplast genomic information hinders molecular research and phylogenetic analysis on ginger. We introduced the complete [...] Read more.

Zingiber officinale, commonly known as ginger, is an important plant of the family Zingiberaceae and is widely used as an herbal medicine and condiment. The lack of chloroplast genomic information hinders molecular research and phylogenetic analysis on ginger. We introduced the complete chloroplast genome of Z. officinale and identified its phylogenetic position in Zingiberaceae. The chloroplast genome of Z. officinale is 162,621 bp with a four-part circular structure and 36.1% GC content. All 113 unique genes were annotated. A total of 78 simple sequence repeats (SSRs) and 42 long repeat sequences, which are potential areas for species authentication, were found. Comparative analysis revealed some highly variable regions, including rps16-trnQ-UUG, atpH-atpI, trnT-UGU-trnL-UAA, ycf1, and psaC-ndhE. Moreover, the small single-copy (SSC) region was the most variable region in all four shared regions, indicating that it may be undergoing rapid nucleotide substitution in the family Zingiberaceae. Phylogenetic analysis based on all available chloroplasts of Zingiberales in the National Center for Biotechnology Information indicated that Zingiber is a sister branch to Kaempferia species. The availability of the Z. officinale chloroplast genome provided invaluable data for species-level authentication and phylogenetic analysis and can thus benefit further investigations on species in the family Zingiberaceae. Full article

(This article belongs to the Special Issue Plant Bioinformatics)

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13 pages, 705 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Growth Rate and Nutrient Content of Five Microalgae Species Cultivated in Greenhouses

by Maria N. Metsoviti, George Papapolymerou, Ioannis T. Karapanagiotidis and Nikolaos Katsoulas

Plants 2019, 8(8), 279; https://doi.org/10.3390/plants8080279 - 10 Aug 2019

Cited by 56 | Viewed by 5957

Abstract

The effect of different environmental conditions on the growth rate, biomass production, nutrient composition, and phenolic content of the microalgae species Chlorella vulgaris, Botryococcus braunii, Chlamydomonas reinhardtii, Euglena gracilis, and Nannochloropsis oculata was investigated. The experiments were conducted in [...] Read more.

The effect of different environmental conditions on the growth rate, biomass production, nutrient composition, and phenolic content of the microalgae species Chlorella vulgaris, Botryococcus braunii, Chlamydomonas reinhardtii, Euglena gracilis, and Nannochloropsis oculata was investigated. The experiments were conducted in open bioreactors in a greenhouse in three different periods (during October, March, and June), and in a controlled environment in a closed plant growth chamber. It was found that the growth rate and production of C. vulgaris and B. braunii was higher during March, C. reinhardtii and N. oculata grew better in June, and the growth of E. gracilis was similar in March and June. The lipid content of the biomass of all five species increased with increasing light intensity and temperature, while the nitrogen free extractable (NFE) content decreased and the protein, fiber, moisture, and ash content remained relatively unaffected. The phenolic content varied from species to species with E. gracilis having the highest and N. oculata the lowest content among the species studied. The results can be taken into account when cultivating the different microalgae studied in full scale applications, such as in open raceway bioreactors, where conditions could be adjusted to obtain the most favorable growth conditions, depending on the particular species cultivated. Full article

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14 pages, 4401 KiB

Open AccessEditor’s ChoiceArticle

Antioxidant, Antidiabetic, and Anticholinesterase Activities and Phytochemical Profile of Azorella glabra Wedd

by Immacolata Faraone, Dilip K. Rai, Daniela Russo, Lucia Chiummiento, Eloy Fernandez, Alka Choudhary and Luigi Milella

Plants 2019, 8(8), 265; https://doi.org/10.3390/plants8080265 - 3 Aug 2019

Cited by 32 | Viewed by 5339

Abstract

Oxidative stress is involved in different diseases, such as diabetes and neurodegenerative diseases. The genus Azorella includes about 70 species of flowering plant species; most of them are commonly used as food and in particular as a tea infusion in the Andean region [...] Read more.

Oxidative stress is involved in different diseases, such as diabetes and neurodegenerative diseases. The genus Azorella includes about 70 species of flowering plant species; most of them are commonly used as food and in particular as a tea infusion in the Andean region of South America in folk medicine to treat various chronic diseases. Azorella glabra Wedd. aerial parts were firstly analyzed for their in vitro antioxidant activity using different complementary assays. In particular, radical scavenging activity was tested against biological neutral radical DPPH; ferric reducing power and lipid peroxidation inhibitory capacity (FRAP and Beta-Carotene Bleaching tests) were also determined. The Relative Antioxidant Capacity Index (RACI) was used to compare data obtained by different assays. Then, the inhibitory ability of samples was investigated against α-amylase and α-glucosidase enzymes involved in diabetes and against acetylcholinesterase and butyrylcholinesterase enzymes considered as strategy for the treatment of Parkinson’s or Alzheimer’s diseases. Moreover, the phytochemical profile of the sample showing the highest RACI (1.35) and interesting enzymatic activities (IC₅₀ of 163.54 ± 9.72 and 215.29 ± 17.10 μg/mL in α-glucosidase and acetylcholinesterase inhibition, respectively) was subjected to characterization and quantification of its phenolic composition using LC-MS/MS analysis. In fact, the ethyl acetate fraction derived from ethanol extract by liquid/liquid extraction showed 29 compounds, most of them are cinnamic acid derivatives, flavonoid derivatives, and a terpene. To the best of our knowledge, this is the first report about the evaluation of significant biological activities and phytochemical profile of A. glabra, an important source of health-promoting phytochemicals. Full article

(This article belongs to the Special Issue Medicinal Plants)

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17 pages, 1666 KiB

Open AccessEditor’s ChoiceReview

Biology and Function of miR159 in Plants

by Anthony A. Millar, Allan Lohe and Gigi Wong

Plants 2019, 8(8), 255; https://doi.org/10.3390/plants8080255 - 30 Jul 2019

Cited by 99 | Viewed by 7235

Abstract

MicroR159 (miR159) is ancient, being present in the majority of land plants where it targets a class of regulatory genes called GAMYB or GAMYB-like via highly conserved miR159-binding sites. These GAMYB genes encode R2R3 MYB domain transcription factors that transduce the gibberellin (GA) [...] Read more.

MicroR159 (miR159) is ancient, being present in the majority of land plants where it targets a class of regulatory genes called GAMYB or GAMYB-like via highly conserved miR159-binding sites. These GAMYB genes encode R2R3 MYB domain transcription factors that transduce the gibberellin (GA) signal in the seed aleurone and the anther tapetum. Here, GAMYB plays a conserved role in promoting the programmed cell death of these tissues, where miR159 function appears weak. By contrast, GAMYB is not involved in GA-signaling in vegetative tissues, but rather its expression is deleterious, leading to the inhibition of growth and development. Here, the major function of miR159 is to mediate strong silencing of GAMYB to enable normal growth. Highlighting this requirement of strong silencing are conserved RNA secondary structures associated with the miR159-binding site in GAMYB mRNA that promotes miR159-mediated repression. Although the miR159-GAMYB pathway in vegetative tissues has been implicated in a number of different functions, presently no conserved role for this pathway has emerged. We will review the current knowledge of the different proposed functions of miR159, and how this ancient pathway has been used as a model to help form our understanding of miRNA biology in plants. Full article

(This article belongs to the Special Issue The Role of MicroRNAs in Plants)

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20 pages, 2692 KiB

Open AccessEditor’s ChoiceArticle

Foliar Application of Zinc Oxide Nanoparticles and Zinc Sulfate Boosts the Content of Bioactive Compounds in Habanero Peppers

by Josué I. García-López, Guillermo Niño-Medina, Emilio Olivares-Sáenz, Ricardo H. Lira-Saldivar, Enrique Díaz Barriga-Castro, Rigoberto Vázquez-Alvarado, Pablo A. Rodríguez-Salinas and Francisco Zavala-García

Plants 2019, 8(8), 254; https://doi.org/10.3390/plants8080254 - 30 Jul 2019

Cited by 146 | Viewed by 9711

Abstract

The physiological responses of habanero pepper plants (Capsicum chinense Jacq.) to foliar applications of zinc sulphate and zinc nano-fertilizer were evaluated in greenhouse trials. The effect of the supplement on fruit quality of habanero pepper was particularly observed. Habanero pepper plants were [...] Read more.

The physiological responses of habanero pepper plants (Capsicum chinense Jacq.) to foliar applications of zinc sulphate and zinc nano-fertilizer were evaluated in greenhouse trials. The effect of the supplement on fruit quality of habanero pepper was particularly observed. Habanero pepper plants were grown to maturity, and during the main stages of phenological development, they were treated with foliar applications of Zn at concentrations of 1000 and 2000 mg L⁻¹ in the form of zinc sulfate (ZnSO₄) and zinc oxide nanoparticles (ZnO NPs). Additional Zn was not supplied to the control treatment plants. ZnO NPs at a concentration of 1000 mg L⁻¹ positively affected plant height, stem diameter, and chlorophyll content, and increased fruit yield and biomass accumulation compared to control and ZnSO₄ treatments. ZnO NPs at 2000 mg L⁻¹ negatively affected plant growth but significantly increased fruit quality, capsaicin content by 19.3%, dihydrocapsaicin by 10.9%, and Scoville Heat Units by 16.4%. In addition, at 2000 ZnO NPs mg L⁻¹ also increased content of total phenols and total flavonoids (soluble + bound) in fruits (14.50% and 26.9%, respectively), which resulted in higher antioxidant capacity in ABTS (2,2′azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), DPPH (2,2-diphenyl-1-picrylhydrazyl), and FRAP (ferric reducing antioxidant power) (15.4%, 31.8%, and 20.5%, respectively). These results indicate that application of ZnO NPs could be employed in habanero pepper production to improve yield, quality, and nutraceutical properties of fruits. Full article

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14 pages, 1669 KiB

Open AccessEditor’s ChoiceReview

The Diverse Roles of Auxin in Regulating Leaf Development

by Yuanyuan Xiong and Yuling Jiao

Plants 2019, 8(7), 243; https://doi.org/10.3390/plants8070243 - 23 Jul 2019

Cited by 60 | Viewed by 10482

Abstract

Leaves, the primary plant organs that function in photosynthesis and respiration, have highly organized, flat structures that vary within and among species. In recent years, it has become evident that auxin plays central roles in leaf development, including leaf initiation, blade formation, and [...] Read more.

Leaves, the primary plant organs that function in photosynthesis and respiration, have highly organized, flat structures that vary within and among species. In recent years, it has become evident that auxin plays central roles in leaf development, including leaf initiation, blade formation, and compound leaf patterning. In this review, we discuss how auxin maxima form to define leaf primordium formation. We summarize recent progress in understanding of how spatial auxin signaling promotes leaf blade formation. Finally, we discuss how spatial auxin transport and signaling regulate the patterning of compound leaves and leaf serration. Full article

(This article belongs to the Special Issue From Genes to Shape and Function: Leaf Morphogenesis at Play)

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24 pages, 3660 KiB

Open AccessEditor’s ChoiceReview

What Makes Adventitious Roots?

by Mathieu Gonin, Véronique Bergougnoux, Thu D. Nguyen, Pascal Gantet and Antony Champion

Plants 2019, 8(7), 240; https://doi.org/10.3390/plants8070240 - 22 Jul 2019

Cited by 84 | Viewed by 29787

Abstract

The spermatophyte root system is composed of a primary root that develops from an embryonically formed root meristem, and of different post-embryonic root types: lateral and adventitious roots. Adventitious roots, arising from the stem of the plants, are the main component of the [...] Read more.

The spermatophyte root system is composed of a primary root that develops from an embryonically formed root meristem, and of different post-embryonic root types: lateral and adventitious roots. Adventitious roots, arising from the stem of the plants, are the main component of the mature root system of many plants. Their development can also be induced in response to adverse environmental conditions or stresses. Here, in this review, we report on the morphological and functional diversity of adventitious roots and their origin. The hormonal and molecular regulation of the constitutive and inducible adventitious root initiation and development is discussed. Recent data confirmed the crucial role of the auxin/cytokinin balance in adventitious rooting. Nevertheless, other hormones must be considered. At the genetic level, adventitious root formation integrates the transduction of external signals, as well as a core auxin-regulated developmental pathway that is shared with lateral root formation. The knowledge acquired from adventitious root development opens new perspectives to improve micropropagation by cutting in recalcitrant species, root system architecture of crops such as cereals, and to understand how plants adapted during evolution to the terrestrial environment by producing different post-embryonic root types. Full article

(This article belongs to the Special Issue Root System Structure and Function: A Themed Issue in Honor of Professor Yoav Waisel)

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10 pages, 504 KiB

Open AccessEditor’s ChoiceReview

WRINKLED1, a “Master Regulator” in Transcriptional Control of Plant Oil Biosynthesis

by Que Kong, Ling Yuan and Wei Ma

Plants 2019, 8(7), 238; https://doi.org/10.3390/plants8070238 - 22 Jul 2019

Cited by 47 | Viewed by 6946

Abstract

A majority of plant species generate and accumulate triacylglycerol (TAG) in their seeds, which is the main resource of carbon and energy supporting the process of seedling development. Plant seed oils have broad ranges of uses, being not only important for human diets [...] Read more.

A majority of plant species generate and accumulate triacylglycerol (TAG) in their seeds, which is the main resource of carbon and energy supporting the process of seedling development. Plant seed oils have broad ranges of uses, being not only important for human diets but also renewable feedstock of industrial applications. The WRINKLED1 (WRI1) transcription factor is vital for the transcriptional control of plant oil biosynthetic pathways. Since the identification of the Arabidopsis WRI1 gene (AtWRI1) fifteen years ago, tremendous progress has been made in understanding the functions of WRI1 at multiple levels, ranging from the identification of AtWRI1 target genes to location of the AtWRI1 binding motif, and from discovery of intrinsic structural disorder in WRI1 to fine-tuning of WRI1 modulation by post-translational modifications and protein-protein interactions. The expanding knowledge on the functional understanding of the WRI1 regulatory mechanism not only provides a clearer picture of transcriptional regulation of plant oil biosynthetic pathway, but also helps generate new strategies to better utilize WRI1 for developing novel oil crops. Full article

(This article belongs to the Special Issue Lipid Metabolism in Plants)

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23 pages, 1988 KiB

Open AccessEditor’s ChoiceArticle

Variations of Secondary Metabolites among Natural Populations of Sub-Antarctic Ranunculus Species Suggest Functional Redundancy and Versatility

by Bastien Labarrere, Andreas Prinzing, Thomas Dorey, Emeline Chesneau and Françoise Hennion

Plants 2019, 8(7), 234; https://doi.org/10.3390/plants8070234 - 19 Jul 2019

Cited by 25 | Viewed by 5724

Abstract

Plants produce a high diversity of metabolites which help them sustain environmental stresses and are involved in local adaptation. However, shaped by both the genome and the environment, the patterns of variation of the metabolome in nature are difficult to decipher. Few studies [...] Read more.

Plants produce a high diversity of metabolites which help them sustain environmental stresses and are involved in local adaptation. However, shaped by both the genome and the environment, the patterns of variation of the metabolome in nature are difficult to decipher. Few studies have explored the relative parts of geographical region versus environment or phenotype in metabolomic variability within species and none have discussed a possible effect of the region on the correlations between metabolites and environments or phenotypes. In three sub-Antarctic Ranunculus species, we examined the role of region in metabolite differences and in the relationship between individual compounds and environmental conditions or phenotypic traits. Populations of three Ranunculus species were sampled across similar environmental gradients in two distinct geographical regions in îles Kerguelen. Two metabolite classes were studied, amines (quantified by high-performance liquid chromatography and fluorescence spectrophotometry) and flavonols (quantified by ultra-high-performance liquid chromatography with triple quadrupole mass spectrometry). Depending on regions, the same environment or the same trait may be related to different metabolites, suggesting metabolite redundancy within species. In several cases, a given metabolite showed different or even opposite relations with the same environmental condition or the same trait across the two regions, suggesting metabolite versatility within species. Our results suggest that metabolites may be functionally redundant and versatile within species, both in their response to environments and in their relation with the phenotype. These findings open new perspectives for understanding evolutionary responses of plants to environmental changes. Full article

(This article belongs to the Special Issue Plant Polyamines)

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18 pages, 2190 KiB

Open AccessEditor’s ChoiceArticle

Allelopathic and Autotoxic Effects of Medicago sativa—Derived Allelochemicals

by Bimal Kumar Ghimire, Balkrishna Ghimire, Chang Yeon Yu and Ill-Min Chung

Plants 2019, 8(7), 233; https://doi.org/10.3390/plants8070233 - 18 Jul 2019

Cited by 58 | Viewed by 6799

Abstract

In this study, the allelopathic properties of Medicago sativa on different weeds were investigated under in vitro conditions. The compounds involved in the autotoxicity of M. sativa were analyzed using high-performance liquid chromatography. The extracts of all concentrations inhibited the growth of the [...] Read more.

In this study, the allelopathic properties of Medicago sativa on different weeds were investigated under in vitro conditions. The compounds involved in the autotoxicity of M. sativa were analyzed using high-performance liquid chromatography. The extracts of all concentrations inhibited the growth of the calluses of Digitaria ciliaris, Chenopodium album, Amaranthus lividus, Portulaca oleracea, and Commelina communis. Six allelopathic compounds in alfalfa were identified and quantified, and the most predominant phenolic compounds were salicylic acid and p-hydroxybenzoic acid. Various concentrations (10⁻², 10⁻³, and 10⁻⁵ M) of all the tested phenolic compounds exerted inhibitory effects on callus fresh weight. Rutin, salicylic acid, scopoletin, and quercetin significantly inhibited alfalfa seed germination. Of the seven identified saponins, medicagenic acid saponins exhibited the highest autotoxic effect and significantly lowered seed germination rate. Principal component analysis showed that the phenolic compounds and saponin composition significantly contributed to the different variables. The highly phytotoxic properties of the alfalfa-derived phenolic compounds and saponins indicate that these phytochemicals can be a potential source of bioherbicides. Full article

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20 pages, 1147 KiB

Open AccessEditor’s ChoiceReview

Drought Stress Effects and Olive Tree Acclimation under a Changing Climate

by Cátia Brito, Lia-Tânia Dinis, José Moutinho-Pereira and Carlos M. Correia

Plants 2019, 8(7), 232; https://doi.org/10.3390/plants8070232 - 17 Jul 2019

Cited by 136 | Viewed by 12135

Abstract

Increasing consciousness regarding the nutritional value of olive oil has enhanced the demand for this product and, consequently, the expansion of olive tree cultivation. Although it is considered a highly resilient and tolerant crop to several abiotic stresses, olive growing areas are usually [...] Read more.

Increasing consciousness regarding the nutritional value of olive oil has enhanced the demand for this product and, consequently, the expansion of olive tree cultivation. Although it is considered a highly resilient and tolerant crop to several abiotic stresses, olive growing areas are usually affected by adverse environmental factors, namely, water scarcity, heat and high irradiance, and are especially vulnerable to climate change. In this context, it is imperative to improve agronomic strategies to offset the loss of productivity and possible changes in fruit and oil quality. To develop more efficient and precise measures, it is important to look for new insights concerning response mechanisms to drought stress. In this review, we provided an overview of the global status of olive tree ecology and relevance, as well the influence of environmental abiotic stresses in olive cultivation. Finally, we explored and analysed the deleterious effects caused by drought (e.g., water status and photosynthetic performance impairment, oxidative stress and imbalance in plant nutrition), the most critical stressor to agricultural crops in the Mediterranean region, and the main olive tree responses to withstand this stressor. Full article

(This article belongs to the Section Plant Physiology and Metabolism)

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18 pages, 4432 KiB

Open AccessEditor’s ChoiceArticle

Effect of Selenium on Alleviating Oxidative Stress Caused by a Water Deficit in Cucumber Roots

by Weronika Jóźwiak and Barbara Politycka

Plants 2019, 8(7), 217; https://doi.org/10.3390/plants8070217 - 11 Jul 2019

Cited by 82 | Viewed by 5482

Abstract

The aim of the study was to evaluate the antioxidant activity of selenium in the roots of Cucumis sativus L. seedlings pre-treated with selenium (Se) in the form of sodium selenite at concentrations of 1, 5, and 10 µM, and then subjected to [...] Read more.

The aim of the study was to evaluate the antioxidant activity of selenium in the roots of Cucumis sativus L. seedlings pre-treated with selenium (Se) in the form of sodium selenite at concentrations of 1, 5, and 10 µM, and then subjected to a water deficit (WD). It has been hypothesized that Se, in low concentrations, alleviates an oxidative stress caused by a WD in the cucumber roots. A WD was introduced by the surface dehydration of roots. The aim of the research was to compare the changes accompanying oxidative stress in plants growing in the presence of Se and in its absence. The study concerns the generation of reactive oxygen species (ROS)—superoxide anions (O₂^•−), hydrogen peroxide (H₂O₂), and hydroxyl radicals (^•OH)—as well the activities of the antioxidant enzymes lowering the ROS level—ascorbate peroxidase (APX), peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD). A WD caused oxidative stress, i.e., the enhanced generation of ROS. Selenium at the concentrations of 1 and 5 μM increased the tolerance of cucumber seedlings to oxidative stress caused by a WD by increasing the activities of the antioxidant enzymes, and it also limited the damage of plasma membranes as a result of the inhibition of lipid peroxidation. Full article

(This article belongs to the Special Issue Selenium Metabolism and Accumulation in Plants)

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13 pages, 1343 KiB

Open AccessEditor’s ChoiceReview

On the Ecology of Selenium Accumulation in Plants

by Elizabeth A. H. Pilon-Smits

Plants 2019, 8(7), 197; https://doi.org/10.3390/plants8070197 - 30 Jun 2019

Cited by 66 | Viewed by 7831

Abstract

Plants accumulate and tolerate Se to varying degrees, up to 15,000 mg Se/kg dry weight for Se hyperaccumulators. Plant Se accumulation may exert positive or negative effects on other species in the community. The movement of plant Se into ecological partners may benefit [...] Read more.

Plants accumulate and tolerate Se to varying degrees, up to 15,000 mg Se/kg dry weight for Se hyperaccumulators. Plant Se accumulation may exert positive or negative effects on other species in the community. The movement of plant Se into ecological partners may benefit them at low concentrations, but cause toxicity at high concentrations. Thus, Se accumulation can protect plants against Se-sensitive herbivores and pathogens (elemental defense) and reduce surrounding vegetation cover via high-Se litter deposition (elemental allelopathy). While hyperaccumulators negatively impact Se-sensitive ecological partners, they offer a niche for Se-tolerant partners, including beneficial microbial and pollinator symbionts as well as detrimental herbivores, pathogens, and competing plant species. These ecological effects of plant Se accumulation may facilitate the evolution of Se resistance in symbionts. Conversely, Se hyperaccumulation may evolve driven by increasing Se resistance in herbivores, pathogens, or plant neighbors; Se resistance also evolves in mutualist symbionts, minimizing the plant’s ecological cost. Interesting topics to address in future research are whether the ecological impacts of plant Se accumulation may affect species composition across trophic levels (favoring Se resistant taxa), and to what extent Se hyperaccumulators form a portal for Se into the local food chain and are important for Se cycling in the local ecosystem. Full article

(This article belongs to the Special Issue Selenium Metabolism and Accumulation in Plants)

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17 pages, 2014 KiB

Open AccessEditor’s ChoiceReview

Melatonin Mediated Regulation of Drought Stress: Physiological and Molecular Aspects

by Anket Sharma and Bingsong Zheng

Plants 2019, 8(7), 190; https://doi.org/10.3390/plants8070190 - 26 Jun 2019

Cited by 161 | Viewed by 10225

Abstract

Drought stress adversely effects physiological and biochemical processes of plants, leading to a reduction in plant productivity. Plants try to protect themselves via activation of their internal defense system, but severe drought causes dysfunction of this defense system. The imbalance between generation and [...] Read more.

Drought stress adversely effects physiological and biochemical processes of plants, leading to a reduction in plant productivity. Plants try to protect themselves via activation of their internal defense system, but severe drought causes dysfunction of this defense system. The imbalance between generation and scavenging of reactive oxygen species (ROS) leads to oxidative stress. Melatonin, a multifunctional molecule, has the potential to protect plants from the adverse effects of drought stress by enhancing the ROS scavenging efficiency. It helps in protection of photosynthetic apparatus and reduction of drought induced oxidative stress. Melatonin regulates plant processes at a molecular level, which results in providing better resistance against drought stress. In this review, the authors have discussed various physiological and molecular aspects regulated by melatonin in plants under drought conditions, along with their underlying mechanisms. Full article

(This article belongs to the Special Issue Plant Responses to Water-Deficit Stress)

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13 pages, 763 KiB

Open AccessEditor’s ChoiceReview

Reactive Oxygen Species as Potential Drivers of the Seed Aging Process

by Katarzyna Kurek, Beata Plitta-Michalak and Ewelina Ratajczak

Plants 2019, 8(6), 174; https://doi.org/10.3390/plants8060174 - 14 Jun 2019

Cited by 135 | Viewed by 8558

Abstract

Seeds are an important life cycle stage because they guarantee plant survival in unfavorable environmental conditions and the transfer of genetic information from parents to offspring. However, similar to every organ, seeds undergo aging processes that limit their viability and ultimately cause the [...] Read more.

Seeds are an important life cycle stage because they guarantee plant survival in unfavorable environmental conditions and the transfer of genetic information from parents to offspring. However, similar to every organ, seeds undergo aging processes that limit their viability and ultimately cause the loss of their basic property, i.e., the ability to germinate. Seed aging is a vital economic and scientific issue that is related to seed resistance to an array of factors, both internal (genetic, structural, and physiological) and external (mainly storage conditions: temperature and humidity). Reactive oxygen species (ROS) are believed to initiate seed aging via the degradation of cell membrane phospholipids and the structural and functional deterioration of proteins and genetic material. Researchers investigating seed aging claim that the effective protection of genetic resources requires an understanding of the reasons for senescence of seeds with variable sensitivity to drying and long-term storage. Genomic integrity considerably affects seed viability and vigor. The deterioration of nucleic acids inhibits transcription and translation and exacerbates reductions in the activity of antioxidant system enzymes. All of these factors significantly limit seed viability. Full article

(This article belongs to the Special Issue Genetics of Seed Germination and Growth)

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15 pages, 2339 KiB

Open AccessEditor’s ChoiceArticle

Waterlogging Causes Early Modification in the Physiological Performance, Carotenoids, Chlorophylls, Proline, and Soluble Sugars of Cucumber Plants

by T. Casey Barickman, Catherine R. Simpson and Carl E. Sams

Plants 2019, 8(6), 160; https://doi.org/10.3390/plants8060160 - 8 Jun 2019

Cited by 105 | Viewed by 7889

Abstract

Waterlogging occurs because of poor soil drainage and/or excessive rainfall and is a serious abiotic stress affecting plant growth because of declining oxygen supplied to submerged tissues. Although cucumber (Cucumis sativus L.) is sensitive to waterlogging, its ability to generate adventitious roots [...] Read more.

Waterlogging occurs because of poor soil drainage and/or excessive rainfall and is a serious abiotic stress affecting plant growth because of declining oxygen supplied to submerged tissues. Although cucumber (Cucumis sativus L.) is sensitive to waterlogging, its ability to generate adventitious roots facilitates gas diffusion and increases plant survival when oxygen concentrations are low. To understand the physiological responses to waterlogging, a 10-day waterlogging experiment was conducted. The objective of this study was to measure the photosynthetic and key metabolites of cucumber plants under waterlogging conditions for 10 days. Plants were also harvested at the end of 10 days and analyzed for plant height (ht), leaf number and area, fresh mass (FM), dry mass (DM), chlorophyll (Chl), carotenoid (CAR), proline, and soluble sugars. Results indicated that cucumber plants subjected to the 10-day waterlogging stress conditions were stunted, had fewer leaves, and decreased leaf area, FM, and DM. There were differences in physiological performance, Chl, CAR, proline, and soluble sugars. Overall, waterlogging stress decreased net photosynthesis (A), having a negative effect on biomass accumulation. However, these decreases were also dependent on other factors, such as plant size, morphology, and water use efficiency (WUE) that played a role in the overall metabolism of the plant. Full article

(This article belongs to the Section Plant Physiology and Metabolism)

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13 pages, 1641 KiB

Open AccessEditor’s ChoiceReview

Herbicide Resistance Management: Recent Developments and Trends

by Hugh J. Beckie, Michael B. Ashworth and Ken C. Flower

Plants 2019, 8(6), 161; https://doi.org/10.3390/plants8060161 - 8 Jun 2019

Cited by 87 | Viewed by 10727

Abstract

This review covers recent developments and trends in herbicide-resistant (HR) weed management in agronomic field crops. In countries where input-intensive agriculture is practiced, these developments and trends over the past decade include renewed efforts by the agrichemical industry in herbicide discovery, cultivation of [...] Read more.

This review covers recent developments and trends in herbicide-resistant (HR) weed management in agronomic field crops. In countries where input-intensive agriculture is practiced, these developments and trends over the past decade include renewed efforts by the agrichemical industry in herbicide discovery, cultivation of crops with combined (stacked) HR traits, increasing reliance on preemergence vs. postemergence herbicides, breeding for weed-competitive crop cultivars, expansion of harvest weed seed control practices, and advances in site-specific or precision weed management. The unifying framework or strategy underlying these developments and trends is mitigation of viable weed seeds into the soil seed bank and maintaining low weed seed banks to minimize population proliferation, evolution of resistance to additional herbicidal sites of action, and spread. A key question going forward is: how much weed control is enough to consistently achieve the goal of low weed seed banks? The vision for future HR weed management programs must be sustained crop production and profitability with reduced herbicide (particularly glyphosate) dependency. Full article

(This article belongs to the Special Issue Herbicide Resistance in Plants)

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12 pages, 2166 KiB

Open AccessEditor’s ChoiceReview

Ascorbic Acid and Ozone: Novel Perspectives to Explain an Elusive Relationship

by Erika Bellini and Mario C. De Tullio

Plants 2019, 8(5), 122; https://doi.org/10.3390/plants8050122 - 9 May 2019

Cited by 46 | Viewed by 5353

Abstract

A huge amount of studies highlighted the importance of high ascorbic acid (AA) content in ozone tolerance, yet the relationship between them appears more complex than a simple direct correlation. Sometimes the connection is clear, for example, two Arabidopsis mutants defective in the [...] Read more.

A huge amount of studies highlighted the importance of high ascorbic acid (AA) content in ozone tolerance, yet the relationship between them appears more complex than a simple direct correlation. Sometimes the connection is clear, for example, two Arabidopsis mutants defective in the main AA biosynthetic pathway (vtc mutants) were identified by means of their ozone sensitivity. However, some low-AA containing mutants are relatively tolerant, suggesting that AA location/availability could be more relevant than total content. A clear distinction should also be made between ozone tolerance obtained when AA content is increased by experimental supplementation (exogenous AA), and the physiological role of plant-synthesized AA (endogenous AA), whose amount is apparently subjected to tight regulation. Recent findings about the role of AA in signal transduction and epigenetic regulation of gene expression open new routes to further research. Full article

(This article belongs to the Special Issue Ozone Tolerance Mechanisms)

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13 pages, 1104 KiB

Open AccessEditor’s ChoiceArticle

Effect of Phosphorus Fertilization on the Growth, Photosynthesis, Nitrogen Fixation, Mineral Accumulation, Seed Yield, and Seed Quality of a Soybean Low-Phytate Line

by Nisar Ahmad Taliman, Qin Dong, Kohei Echigo, Victor Raboy and Hirofumi Saneoka

Plants 2019, 8(5), 119; https://doi.org/10.3390/plants8050119 - 8 May 2019

Cited by 80 | Viewed by 8711

Abstract

Crop seed phosphorus (P) is primarily stored in the form of phytate, which is generally indigestible by monogastric animals. Low-phytate soybean lines have been developed to solve various problems related to seed phytate. There is little information available on the effects of P [...] Read more.

Crop seed phosphorus (P) is primarily stored in the form of phytate, which is generally indigestible by monogastric animals. Low-phytate soybean lines have been developed to solve various problems related to seed phytate. There is little information available on the effects of P fertilization on productivity, physiological characteristics, and seed yield and quality in low-phytate soybeans. To address this knowledge gap, studies were conducted with a low-phytate line and two normal-phytate cultivars from western Japan when grown under high- and low-P fertilization. The whole plant dry weight, leaf photosynthesis, dinitrogen fixation, and nodule dry weight at the flowering stage were higher in the higher P application level, but were not different between the low-phytate line and normal-phytate cultivars. As expected, seed yield was higher in the higher level of P application for all lines. Notably, it was higher in the low-phytate line as compared with the normal-phytate cultivars at both levels of fertilizer P. The total P concentration in the seeds of the low-phytate line was the same as that of the normal-phytate cultivars, but the phytate P concentration in the low-phytate line was about 50% less than that of the normal-phytate cultivars. As a result the molar ratio of phytic acid to Zn, Fe, Mn, and Cu in seed were also significantly lower in the low-phytate line. From these results, it can be concluded that growth after germination, leaf photosynthesis, nitrogen fixation, yield and seed quality were not less in the low-phytate soybean line as compared with two unrelated normal-phytate cultivars currently grown in Japan, and that low-phytate soybeans may improve the bioavailability of microelements. Full article

(This article belongs to the Special Issue Phytic Acid and Mineral Biofortification Strategies: From Plant Science to Breeding and Biotechnological Approaches)

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12 pages, 2643 KiB

Open AccessEditor’s ChoiceArticle

Mutation of Inositol 1,3,4-trisphosphate 5/6-kinase6 Impairs Plant Growth and Phytic Acid Synthesis in Rice

by Meng Jiang, Yang Liu, Yanhua Liu, Yuanyuan Tan, Jianzhong Huang and Qingyao Shu

Plants 2019, 8(5), 114; https://doi.org/10.3390/plants8050114 - 29 Apr 2019

Cited by 56 | Viewed by 5460

Abstract

Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK) is encoded by six genes in rice (OsITPK1-6). A previous study had shown that nucleotide substitutions of OsITPK6 could significantly lower the phytic acid content in rice grains. In the present study, the possibility of establishing a [...] Read more.

Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK) is encoded by six genes in rice (OsITPK1-6). A previous study had shown that nucleotide substitutions of OsITPK6 could significantly lower the phytic acid content in rice grains. In the present study, the possibility of establishing a genome editing-based method for breeding low-phytic acid cultivars in rice was explored, in conjunction with the functional determination of OsITPK6. Four OsITPK6 mutant lines were generated by targeted mutagenesis of the gene’s first exon using the CRISPR/Cas9 method, one (ositpk6_1) with a 6-bp in-frame deletion, and other three with frameshift mutations (ositpk6_2, _3, and _4). The frameshift mutations severely impaired plant growth and reproduction, while the effect of ositpk6_1 was relatively limited. The mutant lines ositpk6_1 and _2 had significantly lower levels (−10.1% and −32.1%) of phytic acid and higher levels (4.12- and 5.18-fold) of inorganic phosphorus compared with the wild-type (WT) line. The line ositpk6_1 also showed less tolerance to osmotic stresses. Our research demonstrates that mutations of OsITPK6, while effectively reducing phytic acid biosynthesis in rice grain, could significantly impair plant growth and reproduction. Full article

(This article belongs to the Special Issue Phytic Acid and Mineral Biofortification Strategies: From Plant Science to Breeding and Biotechnological Approaches)

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16 pages, 874 KiB

Open AccessEditor’s ChoiceArticle

Effect of Selenium Biofortification and Beneficial Microorganism Inoculation on Yield, Quality and Antioxidant Properties of Shallot Bulbs

by Nadezhda Golubkina, Svetlana Zamana, Timofei Seredin, Pavel Poluboyarinov, Sergei Sokolov, Helene Baranova, Leonid Krivenkov, Laura Pietrantonio and Gianluca Caruso

Plants 2019, 8(4), 102; https://doi.org/10.3390/plants8040102 - 17 Apr 2019

Cited by 74 | Viewed by 5483

Abstract

Plant biofortification with selenium in interaction with the application of an arbuscular mycorrhizal fungi (AMF)-based formulate, with the goal of enhancing Se bioavailability, is beneficial for the development of the environmentally friendly production of functional food with a high content of this microelement. [...] Read more.

Plant biofortification with selenium in interaction with the application of an arbuscular mycorrhizal fungi (AMF)-based formulate, with the goal of enhancing Se bioavailability, is beneficial for the development of the environmentally friendly production of functional food with a high content of this microelement. Research was carried out in order to assess the effects of an AMF-based formulate and a non-inoculated control in factorial combination with two selenium treatments with an organic (selenocystine) or inorganic form (sodium selenate) and a non-treated control on the yield, quality, antioxidant properties, and elemental composition of shallot (Allium cepa L. Aggregatum group). Selenocystine showed the best effect on the growth and yield of mycorrhized plants, whereas sodium selenate was the most effective on the non-inoculated plants. The soluble solids, total sugars, monosaccharides, titratable acidity, and proteins attained higher values upon AMF inoculation. Sodium selenate resulted in higher soluble solids, total sugars and monosaccharide content, and titratable acidity than the non-treated control, and it also resulted in higher monosaccharides when compared to selenocystine; the latter showed higher protein content than the control. Calcium, Na, S, and Cl bulb concentrations were higher in the plants inoculated with the beneficial microorganisms. Calcium and sodium concentrations were higher in the bulbs of plants treated with both the selenium forms than in the control. Selenocystine-treated plants showed enhanced accumulation of sulfur and chlorine compared to the untreated plants. The AMF inoculation increased the bulb selenium content by 530%, and the Se biofortification with selenocystine and sodium selenate increased this value by 36% and 21%, respectively, compared to control plants. The AMF-based formulate led to increases in ascorbic acid and antioxidant activity when compared to the non-inoculated control. The bulb ascorbic acid was increased by fortification with both selenium forms when compared to the non-treated control. The results of our investigation showed that both AMF and selenium application represent environmentally friendly strategies to enhance the overall yield and quality performances of shallot bulbs, as well as their selenium content. Full article

(This article belongs to the Special Issue Selenium Metabolism and Accumulation in Plants)

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12 pages, 1222 KiB

Open AccessEditor’s ChoiceArticle

Blue Light added with Red LEDs Enhance Growth Characteristics, Pigments Content, and Antioxidant Capacity in Lettuce, Spinach, Kale, Basil, and Sweet Pepper in a Controlled Environment

by Most Tahera Naznin, Mark Lefsrud, Valerie Gravel and Md Obyedul Kalam Azad

Plants 2019, 8(4), 93; https://doi.org/10.3390/plants8040093 - 8 Apr 2019

Cited by 177 | Viewed by 12407

Abstract

The aim of this study was to investigate the different combinations of red (R) and blue (B) light emitting diode (LEDs’) lighting effects on growth, pigment content, and antioxidant capacity in lettuce, spinach, kale, basil, and pepper in a growth chamber. The growth [...] Read more.

The aim of this study was to investigate the different combinations of red (R) and blue (B) light emitting diode (LEDs’) lighting effects on growth, pigment content, and antioxidant capacity in lettuce, spinach, kale, basil, and pepper in a growth chamber. The growth chamber was equipped with R and B light percentages based on total light intensity: 83% R + 17% B; 91% R + 9% B; 95% R + 5% B; and control was 100% R. The photosynthetic photon flux density (PPFD), photoperiod, temperature, and relative humidity of the growth chamber were maintained at 200 ± 5 μmol m⁻² s⁻¹, 16 h, 25/21 ± 2.5 °C, and 65 ± 5%, respectively. It is observed that the plant height of lettuce, kale, and pepper was significantly increased under 100% R light, whereas the plant height of spinach and basil did not show any significant difference. The total leaf number of basil and pepper was significantly increased under the treatment of 95% R + 5% B light, while no significant difference was observed for other plant species in the same treatment. Overall, the fresh and dry mass of the studied plants was increased under 91% R + 9% B and 95% R + 5% B light treatment. The significantly higher flower and fruit numbers of pepper were observed under the 95% R + 5% B treatment. The chlorophyll a, chlorophyll b, and total chlorophyll content of lettuce, spinach, basil, and pepper was significantly increased under the 91% R + 9% B treatment while the chlorophyll content of kale was increased under the 95% R + 5% B light treatment. The total carotenoid content of lettuce and spinach was higher in the 91% R + 9% B treatment whereas the carotenoid content of kale, basil, and pepper was increased under the 83% R + 17% B treatment. The antioxidant capacity of the lettuce, spinach, and kale was increased under the 83% R + 17% B treatment while basil and pepper were increased under the 91% R + 9% B treatment. This result indicates that the addition of B light is essential with R light to enhance growth, pigment content, and antioxidant capacity of the vegetable plant in a controlled environment. Moreover, the percentage of B with R light is plant species dependent. Full article

(This article belongs to the Section Phytochemistry)

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9 pages, 12531 KiB

Open AccessEditor’s ChoiceArticle

Cytokinin-Dependent Control of GH3 Group II Family Genes in the Arabidopsis Root

by Emanuela Pierdonati, Simon Josef Unterholzner, Elena Salvi, Noemi Svolacchia, Gaia Bertolotti, Raffaele Dello Ioio, Sabrina Sabatini and Riccardo Di Mambro

Plants 2019, 8(4), 94; https://doi.org/10.3390/plants8040094 - 8 Apr 2019

Cited by 31 | Viewed by 5297

Abstract

The Arabidopsis root is a dynamic system where the interaction between different plant hormones controls root meristem activity and, thus, organ growth. In the root, a characteristic graded distribution of the hormone auxin provides positional information, coordinating the proliferating and differentiating cell status. [...] Read more.

The Arabidopsis root is a dynamic system where the interaction between different plant hormones controls root meristem activity and, thus, organ growth. In the root, a characteristic graded distribution of the hormone auxin provides positional information, coordinating the proliferating and differentiating cell status. The hormone cytokinin shapes this gradient by positioning an auxin minimum in the last meristematic cells. This auxin minimum triggers a cell developmental switch necessary to start the differentiation program, thus, regulating the root meristem size. To position the auxin minimum, cytokinin promotes the expression of the IAA-amido synthase group II gene GH3.17, which conjugates auxin with amino acids, in the most external layer of the root, the lateral root cap tissue. Since additional GH3 genes are expressed in the root, we questioned whether cytokinin to position the auxin minimum also operates via different GH3 genes. Here, we show that cytokinin regulates meristem size by activating the expression of GH3.5 and GH3.6 genes, in addition to GH3.17. Thus, cytokinin activity provides a robust control of auxin activity in the entire organ necessary to regulate root growth. Full article

(This article belongs to the Special Issue Plant Development and Organogenesis: From Basic Principles to Applied Research)

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21 pages, 3799 KiB

Open AccessEditor’s ChoiceReview

Post-Translational Modification of Proteins Mediated by Nitro-Fatty Acids in Plants: Nitroalkylation

by Lorena Aranda-Caño, Beatriz Sánchez-Calvo, Juan C. Begara-Morales, Mounira Chaki, Capilla Mata-Pérez, María N. Padilla, Raquel Valderrama and Juan B. Barroso

Plants 2019, 8(4), 82; https://doi.org/10.3390/plants8040082 - 29 Mar 2019

Cited by 26 | Viewed by 6126

Abstract

Nitrate fatty acids (NO₂-FAs) are considered reactive lipid species derived from the non-enzymatic oxidation of polyunsaturated fatty acids by nitric oxide (NO) and related species. Nitrate fatty acids are powerful biological electrophiles which can react with biological nucleophiles such as glutathione [...] Read more.

Nitrate fatty acids (NO₂-FAs) are considered reactive lipid species derived from the non-enzymatic oxidation of polyunsaturated fatty acids by nitric oxide (NO) and related species. Nitrate fatty acids are powerful biological electrophiles which can react with biological nucleophiles such as glutathione and certain protein–amino acid residues. The adduction of NO₂-FAs to protein targets generates a reversible post-translational modification called nitroalkylation. In different animal and human systems, NO₂-FAs, such as nitro-oleic acid (NO₂-OA) and conjugated nitro-linoleic acid (NO₂-cLA), have cytoprotective and anti-inflammatory influences in a broad spectrum of pathologies by modulating various intracellular pathways. However, little knowledge on these molecules in the plant kingdom exists. The presence of NO₂-OA and NO₂-cLA in olives and extra-virgin olive oil and nitro-linolenic acid (NO₂-Ln) in Arabidopsis thaliana has recently been detected. Specifically, NO₂-Ln acts as a signaling molecule during seed and plant progression and beneath abiotic stress events. It can also release NO and modulate the expression of genes associated with antioxidant responses. Nevertheless, the repercussions of nitroalkylation on plant proteins are still poorly known. In this review, we demonstrate the existence of endogenous nitroalkylation and its effect on the in vitro activity of the antioxidant protein ascorbate peroxidase. Full article

(This article belongs to the Special Issue Nitric Oxide Signaling in Plants)

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20 pages, 1640 KiB

Open AccessEditor’s ChoiceReview

Role of Silicon in Mitigation of Heavy Metal Stresses in Crop Plants

by Javaid Akhter Bhat, S. M. Shivaraj, Pritam Singh, Devanna B. Navadagi, Durgesh Kumar Tripathi, Prasanta K. Dash, Amolkumar U. Solanke, Humira Sonah and Rupesh Deshmukh

Plants 2019, 8(3), 71; https://doi.org/10.3390/plants8030071 - 21 Mar 2019

Cited by 288 | Viewed by 16028

Abstract

Over the past few decades, heavy metal contamination in soil and water has increased due to anthropogenic activities. The higher exposure of crop plants to heavy metal stress reduces growth and yield, and affect the sustainability of agricultural production. In this regard, the [...] Read more.

Over the past few decades, heavy metal contamination in soil and water has increased due to anthropogenic activities. The higher exposure of crop plants to heavy metal stress reduces growth and yield, and affect the sustainability of agricultural production. In this regard, the use of silicon (Si) supplementation offers a promising prospect since numerous studies have reported the beneficial role of Si in mitigating stresses imposed by biotic as well as abiotic factors including heavy metal stress. The fundamental mechanisms involved in the Si-mediated heavy metal stress tolerance include reduction of metal ions in soil substrate, co-precipitation of toxic metals, metal-transport related gene regulation, chelation, stimulation of antioxidants, compartmentation of metal ions, and structural alterations in plants. Exogenous application of Si has been well documented to increase heavy metal tolerance in numerous plant species. The beneficial effects of Si are particularly evident in plants able to accumulate high levels of Si. Consequently, to enhance metal tolerance in plants, the inherent genetic potential for Si uptake should be improved. In the present review, we have discussed the potential role and mechanisms involved in the Si-mediated alleviation of metal toxicity as well as different approaches for enhancing Si-derived benefits in crop plants. Full article

(This article belongs to the Special Issue Plant Responses and Tolerance to Metal/Metalloid Toxicity)

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19 pages, 4640 KiB

Open AccessEditor’s ChoiceArticle

Selenium Biofortification Differentially Affects Sulfur Metabolism and Accumulation of Phytochemicals in Two Rocket Species (Eruca Sativa Mill. and Diplotaxis Tenuifolia) Grown in Hydroponics

by Stefano Dall’Acqua, Andrea Ertani, Elizabeth A.H. Pilon-Smits, Marta Fabrega-Prats and Michela Schiavon

Plants 2019, 8(3), 68; https://doi.org/10.3390/plants8030068 - 16 Mar 2019

Cited by 40 | Viewed by 5623

Abstract

Biofortification can be exploited to enrich plants in selenium (Se), an essential micronutrient for humans. Selenium as selenate was supplied to two rocket species, Eruca sativa Mill. (salad rocket) and Diplotaxis tenuifolia (wild rocket), at 0–40 μM in hydroponics and its effects on [...] Read more.

Biofortification can be exploited to enrich plants in selenium (Se), an essential micronutrient for humans. Selenium as selenate was supplied to two rocket species, Eruca sativa Mill. (salad rocket) and Diplotaxis tenuifolia (wild rocket), at 0–40 μM in hydroponics and its effects on the content and profile of sulphur (S)-compounds and other phytochemicals was evaluated. D. tenuifolia accumulated more total Se and selenocysteine than E. sativa, concentrating up to ~300 mg Se kg⁻¹ dry weight from 10–40 μM Se. To ensure a safe and adequate Se intake, 30 and 4 g fresh leaf material from E. sativa grown with 5 and 10–20 μM Se, respectively or 4 g from D. tenuifolia supplied with 5 μM Se was estimated to be optimal for consumption. Selenium supplementation at or above 10 μM differentially affected S metabolism in the two species in terms of the transcription of genes involved in S assimilation and S-compound accumulation. Also, amino acid content decreased with Se in E. sativa but increased in D. tenuifolia and the amount of phenolics was more reduced in D. tenuifolia. In conclusion, selenate application in hydroponics allowed Se enrichment of rocket. Furthermore, Se at low concentration (5 μM) did not significantly affect accumulation of phytochemicals and plant defence S-metabolites. Full article

(This article belongs to the Special Issue Selenium Metabolism and Accumulation in Plants)

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18 pages, 2489 KiB

Open AccessEditor’s ChoiceArticle

Profiling the Abiotic Stress Responsive microRNA Landscape of Arabidopsis thaliana

by Joseph L. Pegler, Jackson M. J. Oultram, Christopher P. L. Grof and Andrew L. Eamens

Plants 2019, 8(3), 58; https://doi.org/10.3390/plants8030058 - 10 Mar 2019

Cited by 53 | Viewed by 6559

Abstract

It is well established among interdisciplinary researchers that there is an urgent need to address the negative impacts that accompany climate change. One such negative impact is the increased prevalence of unfavorable environmental conditions that significantly contribute to reduced agricultural yield. Plant microRNAs [...] Read more.

It is well established among interdisciplinary researchers that there is an urgent need to address the negative impacts that accompany climate change. One such negative impact is the increased prevalence of unfavorable environmental conditions that significantly contribute to reduced agricultural yield. Plant microRNAs (miRNAs) are key gene expression regulators that control development, defense against invading pathogens and adaptation to abiotic stress. Arabidopsis thaliana (Arabidopsis) can be readily molecularly manipulated, therefore offering an excellent experimental system to alter the profile of abiotic stress responsive miRNA/target gene expression modules to determine whether such modification enables Arabidopsis to express an altered abiotic stress response phenotype. Towards this goal, high throughput sequencing was used to profile the miRNA landscape of Arabidopsis whole seedlings exposed to heat, drought and salt stress, and identified 121, 123 and 118 miRNAs with a greater than 2-fold altered abundance, respectively. Quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) was next employed to experimentally validate miRNA abundance fold changes, and to document reciprocal expression trends for the target genes of miRNAs determined abiotic stress responsive. RT-qPCR also demonstrated that each miRNA/target gene expression module determined to be abiotic stress responsive in Arabidopsis whole seedlings was reflective of altered miRNA/target gene abundance in Arabidopsis root and shoot tissues post salt stress exposure. Taken together, the data presented here offers an excellent starting platform to identify the miRNA/target gene expression modules for future molecular manipulation to generate plant lines that display an altered response phenotype to abiotic stress. Full article

(This article belongs to the Special Issue The Role of MicroRNAs in Plants)

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13 pages, 672 KiB

Open AccessEditor’s ChoiceReview

Role of Nitrate Reductase in NO Production in Photosynthetic Eukaryotes

by Manuel Tejada-Jimenez, Angel Llamas, Aurora Galván and Emilio Fernández

Plants 2019, 8(3), 56; https://doi.org/10.3390/plants8030056 - 6 Mar 2019

Cited by 53 | Viewed by 12716

Abstract

Nitric oxide is a gaseous secondary messenger that is critical for proper cell signaling and plant survival when exposed to stress. Nitric oxide (NO) synthesis in plants, under standard phototrophic oxygenic conditions, has long been a very controversial issue. A few algal strains [...] Read more.

Nitric oxide is a gaseous secondary messenger that is critical for proper cell signaling and plant survival when exposed to stress. Nitric oxide (NO) synthesis in plants, under standard phototrophic oxygenic conditions, has long been a very controversial issue. A few algal strains contain NO synthase (NOS), which appears to be absent in all other algae and land plants. The experimental data have led to the hypothesis that molybdoenzyme nitrate reductase (NR) is the main enzyme responsible for NO production in most plants. Recently, NR was found to be a necessary partner in a dual system that also includes another molybdoenzyme, which was renamed NO-forming nitrite reductase (NOFNiR). This enzyme produces NO independently of the molybdenum center of NR and depends on the NR electron transport chain from NAD(P)H to heme. Under the circumstances in which NR is not present or active, the existence of another NO-forming system that is similar to the NOS system would account for NO production and NO effects. PII protein, which senses and integrates the signals of the C–N balance in the cell, likely has an important role in organizing cell responses. Here, we critically analyze these topics. Full article

(This article belongs to the Special Issue Nitric Oxide Signaling in Plants)

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30 pages, 649 KiB

Open AccessEditor’s ChoiceReview

Bioactive Profile of Various Salvia officinalis L. Preparations

by Martina Jakovljević, Stela Jokić, Maja Molnar, Midhat Jašić, Jurislav Babić, Huska Jukić and Ines Banjari

Plants 2019, 8(3), 55; https://doi.org/10.3390/plants8030055 - 6 Mar 2019

Cited by 94 | Viewed by 11334

Abstract

Salvia officinalis L., also known as the “Salvation Plant”, has been long used and well-documented in traditional medicine around the globe. Its bioactive compounds, and especially its polyphenol profile, have been extensively researched and reviewed. However, sage’s beneficial effects reach much further, and [...] Read more.

Salvia officinalis L., also known as the “Salvation Plant”, has been long used and well-documented in traditional medicine around the globe. Its bioactive compounds, and especially its polyphenol profile, have been extensively researched and reviewed. However, sage’s beneficial effects reach much further, and nowadays, with a range of new extraction techniques, we are discovering new components with new therapeutic effects, especially in the context of neurodegenerative diseases and various carcinomas. This review describes the bioactive profile of various sage preparations depending on the extraction techniques and extraction parameters, and this review lists the newest research findings on its health effects. Full article

(This article belongs to the Section Phytochemistry)

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14 pages, 2450 KiB

Open AccessEditor’s ChoiceReview

Nitric Oxide: Its Generation and Interactions with Other Reactive Signaling Compounds

by John T. Hancock and Steven J. Neill

Plants 2019, 8(2), 41; https://doi.org/10.3390/plants8020041 - 12 Feb 2019

Cited by 80 | Viewed by 6311

Abstract

Nitric oxide (NO) is an immensely important signaling molecule in animals and plants. It is involved in plant reproduction, development, key physiological responses such as stomatal closure, and cell death. One of the controversies of NO metabolism in plants is the identification of [...] Read more.

Nitric oxide (NO) is an immensely important signaling molecule in animals and plants. It is involved in plant reproduction, development, key physiological responses such as stomatal closure, and cell death. One of the controversies of NO metabolism in plants is the identification of enzymatic sources. Although there is little doubt that nitrate reductase (NR) is involved, the identification of a nitric oxide synthase (NOS)-like enzyme remains elusive, and it is becoming increasingly clear that such a protein does not exist in higher plants, even though homologues have been found in algae. Downstream from its production, NO can have several potential actions, but none of these will be in isolation from other reactive signaling molecules which have similar chemistry to NO. Therefore, NO metabolism will take place in an environment containing reactive oxygen species (ROS), hydrogen sulfide (H₂S), glutathione, other antioxidants and within a reducing redox state. Direct reactions with NO are likely to produce new signaling molecules such as peroxynitrite and nitrosothiols, and it is probable that chemical competitions will exist which will determine the ultimate end result of signaling responses. How NO is generated in plants cells and how NO fits into this complex cellular environment needs to be understood. Full article

(This article belongs to the Special Issue Nitric Oxide Signaling in Plants)

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10 pages, 654 KiB

Open AccessEditor’s ChoiceReview

Impact of Nitric Oxide (NO) on the ROS Metabolism of Peroxisomes

by Francisco J. Corpas, Luis A. del Río and José M. Palma

Plants 2019, 8(2), 37; https://doi.org/10.3390/plants8020037 - 10 Feb 2019

Cited by 44 | Viewed by 7438

Abstract

Nitric oxide (NO) is a gaseous free radical endogenously generated in plant cells. Peroxisomes are cell organelles characterized by an active metabolism of reactive oxygen species (ROS) and are also one of the main cellular sites of NO production in higher plants. In [...] Read more.

Nitric oxide (NO) is a gaseous free radical endogenously generated in plant cells. Peroxisomes are cell organelles characterized by an active metabolism of reactive oxygen species (ROS) and are also one of the main cellular sites of NO production in higher plants. In this mini-review, an updated and comprehensive overview is presented of the evidence available demonstrating that plant peroxisomes have the capacity to generate NO, and how this molecule and its derived products, peroxynitrite (ONOO⁻) and S-nitrosoglutathione (GSNO), can modulate the ROS metabolism of peroxisomes, mainly throughout protein posttranslational modifications (PTMs), including S-nitrosation and tyrosine nitration. Several peroxisomal antioxidant enzymes, such as catalase (CAT), copper-zinc superoxide dismutase (CuZnSOD), and monodehydroascorbate reductase (MDAR), have been demonstrated to be targets of NO-mediated PTMs. Accordingly, plant peroxisomes can be considered as a good example of the interconnection existing between ROS and reactive nitrogen species (RNS), where NO exerts a regulatory function of ROS metabolism acting upstream of H₂O₂. Full article

(This article belongs to the Special Issue Nitric Oxide Signaling in Plants)

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29 pages, 3741 KiB

Open AccessEditor’s ChoiceReview

Impact of Climate Change on Crops Adaptation and Strategies to Tackle Its Outcome: A Review

by Ali Raza, Ali Razzaq, Sundas Saher Mehmood, Xiling Zou, Xuekun Zhang, Yan Lv and Jinsong Xu

Plants 2019, 8(2), 34; https://doi.org/10.3390/plants8020034 - 30 Jan 2019

Cited by 1044 | Viewed by 73823

Abstract

Agriculture and climate change are internally correlated with each other in various aspects, as climate change is the main cause of biotic and abiotic stresses, which have adverse effects on the agriculture of a region. The land and its agriculture are being affected [...] Read more.

Agriculture and climate change are internally correlated with each other in various aspects, as climate change is the main cause of biotic and abiotic stresses, which have adverse effects on the agriculture of a region. The land and its agriculture are being affected by climate changes in different ways, e.g., variations in annual rainfall, average temperature, heat waves, modifications in weeds, pests or microbes, global change of atmospheric CO₂ or ozone level, and fluctuations in sea level. The threat of varying global climate has greatly driven the attention of scientists, as these variations are imparting negative impact on global crop production and compromising food security worldwide. According to some predicted reports, agriculture is considered the most endangered activity adversely affected by climate changes. To date, food security and ecosystem resilience are the most concerning subjects worldwide. Climate-smart agriculture is the only way to lower the negative impact of climate variations on crop adaptation, before it might affect global crop production drastically. In this review paper, we summarize the causes of climate change, stresses produced due to climate change, impacts on crops, modern breeding technologies, and biotechnological strategies to cope with climate change, in order to develop climate resilient crops. Revolutions in genetic engineering techniques can also aid in overcoming food security issues against extreme environmental conditions, by producing transgenic plants. Full article

(This article belongs to the Special Issue Plants Reacts to the Changing Environment)

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34 pages, 2478 KiB

Open AccessEditor’s ChoiceReview

Tolerance of Iron-Deficient and -Toxic Soil Conditions in Rice

by Anumalla Mahender, B. P. Mallikarjuna Swamy, Annamalai Anandan and Jauhar Ali

Plants 2019, 8(2), 31; https://doi.org/10.3390/plants8020031 - 28 Jan 2019

Cited by 127 | Viewed by 13893

Abstract

Iron (Fe) deficiency and toxicity are the most widely prevalent soil-related micronutrient disorders in rice (Oryza sativa L.). Progress in rice cultivars with improved tolerance has been hampered by a poor understanding of Fe availability in the soil, the transportation mechanism, and [...] Read more.

Iron (Fe) deficiency and toxicity are the most widely prevalent soil-related micronutrient disorders in rice (Oryza sativa L.). Progress in rice cultivars with improved tolerance has been hampered by a poor understanding of Fe availability in the soil, the transportation mechanism, and associated genetic factors for the tolerance of Fe toxicity soil (FTS) or Fe deficiency soil (FDS) conditions. In the past, through conventional breeding approaches, rice varieties were developed especially suitable for low- and high-pH soils, which indirectly helped the varieties to tolerate FTS and FDS conditions. Rice-Fe interactions in the external environment of soil, internal homeostasis, and transportation have been studied extensively in the past few decades. However, the molecular and physiological mechanisms of Fe uptake and transport need to be characterized in response to the tolerance of morpho-physiological traits under Fe-toxic and -deficient soil conditions, and these traits need to be well integrated into breeding programs. A deeper understanding of the several factors that influence Fe absorption, uptake, and transport from soil to root and above-ground organs under FDS and FTS is needed to develop tolerant rice cultivars with improved grain yield. Therefore, the objective of this review paper is to congregate the different phenotypic screening methodologies for prospecting tolerant rice varieties and their responsible genetic traits, and Fe homeostasis related to all the known quantitative trait loci (QTLs), genes, and transporters, which could offer enormous information to rice breeders and biotechnologists to develop rice cultivars tolerant of Fe toxicity or deficiency. The mechanism of Fe regulation and transport from soil to grain needs to be understood in a systematic manner along with the cascade of metabolomics steps that are involved in the development of rice varieties tolerant of FTS and FDS. Therefore, the integration of breeding with advanced genome sequencing and omics technologies allows for the fine-tuning of tolerant genotypes on the basis of molecular genetics, and the further identification of novel genes and transporters that are related to Fe regulation from FTS and FDS conditions is incredibly important to achieve further success in this aspect. Full article

(This article belongs to the Section Plant Genetics, Genomics and Biotechnology)

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19 pages, 871 KiB

Open AccessEditor’s ChoiceReview

Inhibition of Key Citrus Postharvest Fungal Strains by Plant Extracts In Vitro and In Vivo: A Review

by Jinyin Chen, Yuting Shen, Chuying Chen and Chunpeng Wan

Plants 2019, 8(2), 26; https://doi.org/10.3390/plants8020026 - 22 Jan 2019

Cited by 108 | Viewed by 12296

Abstract

Citrus fruits are subjected to a diversity of postharvest diseases caused by various pathogens during picking, packing, storage and transportation. Green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, are two major postharvest citrus diseases and cause significant economic [...] Read more.

Citrus fruits are subjected to a diversity of postharvest diseases caused by various pathogens during picking, packing, storage and transportation. Green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, are two major postharvest citrus diseases and cause significant economic losses during the commercialization phase. Currently, the control of postharvest citrus diseases relies mainly on the use of synthetic fungicides, which usually result in the resistance against fungal attack, environment pollution and health hazards. In recent years, much attention has been given to the preservation of citrus by naturally isolated edible plant extracts, medicinal plant extracts, Citrus extracts and volatiles, et al. Scientists worldwide devote their time and energy to discover the high effect, low toxicity, safety and inexpensive plant-derived fungicides. The current review will highlight plant-derived fungicides and chemical constituents that aim to inhibit P. digitatum and P. italicum in vitro and in vivo. Coatings enriched with plant extracts could be good alternative methods for Citrus fruits preservation. Problems and prospects of the research and development of plant-derived natural fungicides will also be discussed in this article. Full article

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25 pages, 6393 KiB

Open AccessEditor’s ChoiceReview

Lateral Transport of Organic and Inorganic Solutes

by Emilie Aubry, Sylvie Dinant, Françoise Vilaine, Catherine Bellini and Rozenn Le Hir

Plants 2019, 8(1), 20; https://doi.org/10.3390/plants8010020 - 15 Jan 2019

Cited by 32 | Viewed by 10740

Abstract

Organic (e.g., sugars and amino acids) and inorganic (e.g., K⁺, Na⁺, PO₄²⁻, and SO₄²⁻) solutes are transported long-distance throughout plants. Lateral movement of these compounds between the xylem and the phloem, and vice [...] Read more.

Organic (e.g., sugars and amino acids) and inorganic (e.g., K⁺, Na⁺, PO₄²⁻, and SO₄²⁻) solutes are transported long-distance throughout plants. Lateral movement of these compounds between the xylem and the phloem, and vice versa, has also been reported in several plant species since the 1930s, and is believed to be important in the overall resource allocation. Studies of Arabidopsis thaliana have provided us with a better knowledge of the anatomical framework in which the lateral transport takes place, and have highlighted the role of specialized vascular and perivascular cells as an interface for solute exchanges. Important breakthroughs have also been made, mainly in Arabidopsis, in identifying some of the proteins involved in the cell-to-cell translocation of solutes, most notably a range of plasma membrane transporters that act in different cell types. Finally, in the future, state-of-art imaging techniques should help to better characterize the lateral transport of these compounds on a cellular level. This review brings the lateral transport of sugars and inorganic solutes back into focus and highlights its importance in terms of our overall understanding of plant resource allocation. Full article

(This article belongs to the Special Issue Plant Phloem Development)

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