Plants

19 pages, 2232 KiB

Open AccessArticle

Salinity Effects on Gene Expression, Morphological, and Physio-Biochemical Responses of Stevia rebaudiana Bertoni In Vitro

by Clara R. Azzam, Sudad K. Al-Taweel, Ranya M. Abdel-Aziz, Karim M. Rabea, Alaa I. B. Abou-Sreea, Mostafa M. Rady and Esmat F. Ali

Plants 2021, 10(4), 820; https://doi.org/10.3390/plants10040820 - 20 Apr 2021

Cited by 26 | Viewed by 4360

Abstract

Stevia rebaudiana Bertoni is a little bush, which is cultivated on a large scale in many countries for medicinal purposes and used as a natural sweetener in food products. The present work aims to conduct a protocol for stevia propagation in vitro to [...] Read more.

Stevia rebaudiana Bertoni is a little bush, which is cultivated on a large scale in many countries for medicinal purposes and used as a natural sweetener in food products. The present work aims to conduct a protocol for stevia propagation in vitro to produce and introduce Stevia rebaudiana plants as a new sweetener crop to Egyptian agriculture. To efficiently maximize its propagation, it is important to study the influence of stress factors on the growth and development of Stevia rebaudiana grown in vitro. Two stevia varieties were investigated (Sugar High A3 and Spanti) against salt stress. Leaves were used as the source of explants for callus initiation, regeneration, multiplication and rooting. Some stress-related traits, i.e., photosynthetic pigments, proline contents, and enzyme activity for peroxidase (POD), polyphenol oxidase (PPO), and malate dehydrogenase (MDH) were studied. Murashig and Skoog (MS) medium was supplemented with four NaCl concentrations: 500, 1000, 2000, and 3000 mgL⁻¹, while a salt-free medium was used as the control. The data revealed that salinity negatively affected all studied characters: the number of surviving calli, regeneration%, shoot length, the number of multiple shoots, number of leaf plantlets⁻¹, number of root plantlets⁻¹, and root length. The data also revealed that Sugar High A3 is more tolerant than Spanti. The total chlorophyll content decreased gradually with increasing NaCl concentration. However, the opposite was true for proline content. Isozyme’s fractionation exhibited high levels of variability among the two varieties. Various biochemical parameters associated with salt tolerance were detected in POD. Namely, POD4, POD6, POD 9 at an Rf of 0.34, 0.57, and 0.91 in the Sugar High A3 variety under high salt concentration conditions, as well as POD 10 at an Rf of 0.98 in both varieties under high salt concentrations. In addition, the overexpression of POD 5 and POD 10 at Rf 0.52 and 0.83 was found in both varieties at high NaCl concentrations. Biochemical parameters associated with salt tolerance were detected in PPO (PPO1, PPO2 and PPO4 at an Rf of 0.38, 0.42 and 0.62 in the Sugar High A3 variety under high salt concentrations) and MDH (MDH 3 at an Rf of 0.40 in both varieties at high salt concentrations). Therefore, these could be considered as important biochemical markers associated with salt tolerance and could be applied in stevia breeding programs (marker-assisted selection). This investigation recommends stevia variety Sugar High A3 to be cultivated under salt conditions. Full article

(This article belongs to the Special Issue The Impacts of Anthropogenic Environmental Changes on the Antioxidative Systems in Crops)

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31 pages, 27819 KiB

Open AccessArticle

A Revised Phylogeny of the Mentha spicata Clade Reveals Cryptic Species

by Olivier C. G. Heylen, Nicolas Debortoli, Jonathan Marescaux and Jill K. Olofsson

Plants 2021, 10(4), 819; https://doi.org/10.3390/plants10040819 - 20 Apr 2021

Cited by 12 | Viewed by 5330

Abstract

The genus Mentha is taxonomically and phylogenetically challenging due to complex genomes, polyploidization and an extensive historical nomenclature, potentially hiding cryptic taxa. A straightforward interpretation of phylogenetic relationships within the section Mentha is further hindered by dominant but outdated concepts on historically identified [...] Read more.

The genus Mentha is taxonomically and phylogenetically challenging due to complex genomes, polyploidization and an extensive historical nomenclature, potentially hiding cryptic taxa. A straightforward interpretation of phylogenetic relationships within the section Mentha is further hindered by dominant but outdated concepts on historically identified hybrid taxa. Mentha spicata is traditionally considered to be of hybrid origin, but the evidence for this is weak. Here, we aim to understand the phylogenetic relationships within the section Mentha using large sample sizes and to revisit the hybrid status and identity of M. spicata. We show that two of three traditional species in the subsection Spicatae are polyphyletic, as is the subsection as a whole, while the real number of cryptic species was underestimated. Compared to previous studies we present a fundamentally different phylogeny, with a basal split between M. spicata s.s. and M. longifolia s.s. Cluster analyses of morphological and genotypic data demonstrate that there is a dissociation between morphologically and genotypically defined groups of samples. We did not find any evidence that M. spicata is of hybrid origin, and we conclude its taxonomic status should be revised. The combination of genetic and phenotypic information is essential when evaluating hyperdiverse taxonomic groups. Full article

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17 pages, 2816 KiB

Open AccessEditor’s ChoiceReview

Bioherbicidal Potential of the Essential Oils from Mediterranean Lamiaceae for Weed Control in Organic Farming

by Giuseppe De Mastro, Jihane El Mahdi and Claudia Ruta

Plants 2021, 10(4), 818; https://doi.org/10.3390/plants10040818 - 20 Apr 2021

Cited by 38 | Viewed by 5362

Abstract

In all farming systems, weeds are the most expensive pest to manage, accounting for 30% of potential losses. In organic farming, the problem may be further amplified by restrictions on herbicides, thus making weeds the main problem faced by organic farmers in the [...] Read more.

In all farming systems, weeds are the most expensive pest to manage, accounting for 30% of potential losses. In organic farming, the problem may be further amplified by restrictions on herbicides, thus making weeds the main problem faced by organic farmers in the field. In this sense, much research is focusing on the allelopathic potential of plants as an ecological weed control tool. Many plant species can release allelopathic compounds with high phytotoxicity that can be used in weed control. Species belonging to the Lamiaceae family have been studied widely for this purpose, and their essential oils (EOs) appear to be promising bioherbicides. However, there are still many challenges for their development. Considering these aspects, a review of the bioherbicidal effect of EOs from Mediterranean Lamiaceae could help identify the most effective ones and the challenges for their actual development. Full article

(This article belongs to the Special Issue Sustainable Weed Management)

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14 pages, 3620 KiB

Open AccessReview

Kentucky Bluegrass Invasion in the Northern Great Plains and Prospective Management Approaches to Mitigate Its Spread

by Rakhi Palit, Greta Gramig and Edward S. DeKeyser

Plants 2021, 10(4), 817; https://doi.org/10.3390/plants10040817 - 20 Apr 2021

Cited by 14 | Viewed by 4641

Abstract

Kentucky bluegrass (Poa pratensis L.) is one of the most aggressive grasses invading Northern Great Plains (NGP) grasslands, resulting in substantial native species losses. Highly diverse grasslands dominated by native species are gradually transforming into rangelands largely dominated by non-native Kentucky bluegrass. [...] Read more.

Kentucky bluegrass (Poa pratensis L.) is one of the most aggressive grasses invading Northern Great Plains (NGP) grasslands, resulting in substantial native species losses. Highly diverse grasslands dominated by native species are gradually transforming into rangelands largely dominated by non-native Kentucky bluegrass. Several factors potentially associated with Kentucky bluegrass invasions, including high propagule pressure, thatch formation, climate change, and increasing nitrogen deposition, could determine the future dominance and spread of Kentucky bluegrass in the NGP. Because atmospheric CO₂ is amplifying rapidly, a C3 grass like Kentucky bluegrass might be photosynthetically more efficient than native C4 grasses. As this exotic species shares similar morphological and phenological traits with many native cool-season grasses, controlling it with traditional management practices such as prescribed fire, grazing, herbicides, or combinations of these practices may also impair the growth of native species. Thus, developing effective management practices to combat Kentucky bluegrass spread while facilitating the native species cover is essential. Modifying traditional techniques and embracing science-based adaptive management tools that focus on the ecological interactions of Kentucky bluegrass with the surrounding native species could achieve these desired management goals. Enhancement of the competitiveness of surrounding native species could also be an important consideration for controlling this invasive species. Full article

(This article belongs to the Special Issue Weed Management in Rangeland Environments)

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12 pages, 787 KiB

Open AccessFeature PaperArticle

Broomrape Species Parasitizing Odontarrhena lesbiaca (Brassicaceae) Individuals Act as Nickel Hyperaccumulators

by Panayiotis G. Dimitrakopoulos, Maria Aloupi, Georgios Tetradis and George C. Adamidis

Plants 2021, 10(4), 816; https://doi.org/10.3390/plants10040816 - 20 Apr 2021

Cited by 9 | Viewed by 3583

Abstract

The elemental defense hypothesis supports that metal hyperaccumulation in plant tissues serves as a mechanism underpinning plant resistance to herbivores and pathogens. In this study, we investigate the interaction between Odontarrhena lesbiaca and broomrape parasitic species, in the light of the defense hypothesis [...] Read more.

The elemental defense hypothesis supports that metal hyperaccumulation in plant tissues serves as a mechanism underpinning plant resistance to herbivores and pathogens. In this study, we investigate the interaction between Odontarrhena lesbiaca and broomrape parasitic species, in the light of the defense hypothesis of metal hyperaccumulation. Plant and soil samples collected from three serpentine sites in Lesbos, Greece were analyzed for Ni concentrations. Phelipanche nowackiana and Phelipanche nana were found to infect O. lesbiaca. In both species, Ni concentration decreased gradually from tubercles to shoots and flowers. Specimens of both species with shoot nickel concentrations above 1000 mg.kg⁻¹ were found, showing that they act as nickel hyperaccumulators. Low values of parasite to O. lesbiaca leaf or soil nickel quotients were observed. Orobanche pubescens growing on a serpentine habitat but not in association with O. lesbiaca had very low Ni concentrations in its tissues analogous to excluder plants growing on serpentine soils. Infected O. lesbiaca individuals showed lower leaf nickel concentrations relative to the non-infected ones. Elevated leaf nickel concentration of O. lesbiaca individuals did not prevent parasitic plants to attack them and to hyperaccumulate metals to their tissues, contrary to predictions of the elemental defense hypothesis. Full article

(This article belongs to the Special Issue Metallophytes)

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Graphical abstract

11 pages, 2474 KiB

Open AccessArticle

Phloem-Feeding Herbivores Affect Floral Development and Reproduction in the Etruscan Honeysuckle (Lonicera etrusca Santi)

by Sandra V. Rojas-Nossa, José María Sánchez and Luis Navarro

Plants 2021, 10(4), 815; https://doi.org/10.3390/plants10040815 - 20 Apr 2021

Viewed by 3024

Abstract

Floral development depends on multifactor processes related to genetic, physiological, and ecological pathways. Plants respond to herbivores by activating mechanisms aimed at tolerating, compensating, or avoiding loss of biomass and nutrients, and thereby survive in a complex landscape of interactions. Thus, plants need [...] Read more.

Floral development depends on multifactor processes related to genetic, physiological, and ecological pathways. Plants respond to herbivores by activating mechanisms aimed at tolerating, compensating, or avoiding loss of biomass and nutrients, and thereby survive in a complex landscape of interactions. Thus, plants need to overcome trade-offs between development, growth, and reproduction vs. the initiation of anti-herbivore defences. This study aims to assess the frequency of phloem-feeding herbivores in wild populations of the Etruscan honeysuckle (Lonicera etrusca Santi) and study their effects on floral development and reproduction. The incidence of herbivory by the honeysuckle aphid (Hyadaphis passerinii del Guercio) was assessed in three wild populations of the Iberian Peninsula. The effect of herbivory on floral morphology, micromorphology of stigmas and pollen, floral rewards, pollination, and fruit and seed set were studied. The herbivory by aphids reduces the size of flowers and pollen. Additionally, it stops nectar synthesis and causes malformation in pollen and microstructures of stigmas, affecting pollination. As a consequence, fruit set and seed weight are reduced. This work provides evidence of the changes induced by phloem-feeding herbivores in floral development and functioning that affect the ecological processes necessary to maintain the reproductive success of plants. Full article

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

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11 pages, 1968 KiB

Open AccessArticle

The Effect of Silicon on Osmotic and Drought Stress Tolerance in Wheat Landraces

by Sarah J. Thorne, Susan E. Hartley and Frans J. M. Maathuis

Plants 2021, 10(4), 814; https://doi.org/10.3390/plants10040814 - 20 Apr 2021

Cited by 30 | Viewed by 3596

Abstract

Drought stress reduces annual global wheat yields by 20%. Silicon (Si) fertilisation has been proposed to improve plant drought stress tolerance. However, it is currently unknown if and how Si affects different wheat landraces, especially with respect to their innate Si accumulation properties. [...] Read more.

Drought stress reduces annual global wheat yields by 20%. Silicon (Si) fertilisation has been proposed to improve plant drought stress tolerance. However, it is currently unknown if and how Si affects different wheat landraces, especially with respect to their innate Si accumulation properties. In this study, significant and consistent differences in Si accumulation between landraces were identified, allowing for the classification of high Si accumulators and low Si accumulators. Landraces from the two accumulation groups were then used to investigate the effect of Si during osmotic and drought stress. Si was found to improve growth marginally in high Si accumulators during osmotic stress. However, no significant effect of Si on growth during drought stress was found. It was further found that osmotic stress decreased Si accumulation for all landraces whereas drought increased it. Overall, these results suggest that the beneficial effect of Si commonly reported in similar studies is not universal and that the application of Si fertiliser as a solution to agricultural drought stress requires detailed understanding of genotype-specific responses to Si. Full article

(This article belongs to the Special Issue Water and Ion Transport in Plants: New and Older Trends Meet Together)

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14 pages, 2681 KiB

Open AccessArticle

Comparison of Phenolic and Flavonoid Compound Profiles and Antioxidant and α-Glucosidase Inhibition Properties of Cultivated Soybean (Glycine max) and Wild Soybean (Glycine soja)

by Qianru Chen, Xianxian Wang, Xiaolong Yuan, John Shi, Chengsheng Zhang, Ning Yan and Changliang Jing

Plants 2021, 10(4), 813; https://doi.org/10.3390/plants10040813 - 20 Apr 2021

Cited by 25 | Viewed by 3564

Abstract

Wild soybean (Glycine soja Sieb.et Zucc; WS) has been used as a traditional food in China for many years and contains significantly higher levels of isoflavones than cultivated soybean (Glycine max; CS), but the secondary metabolites, including flavonoids and the [...] Read more.

Wild soybean (Glycine soja Sieb.et Zucc; WS) has been used as a traditional food in China for many years and contains significantly higher levels of isoflavones than cultivated soybean (Glycine max; CS), but the secondary metabolites, including flavonoids and the phenolic composition differences between them, remain unclear. The results showed that WS possessed significantly higher total phenolic and flavonoid content and exhibited better antioxidant and α-glucosidase inhibition activities as well as excellent protective effects against H₂O₂-induced oxidative injury in a human endothelial cell line. Through metabolomic analysis, 642 metabolites were identified, and 238 showed differential expression, with 151 upregulated and 87 downregulated. A total of 79 flavonoid compounds were identified, 42 of which were upregulated in WS. 2′-Hydroxygenistein, garbanzol, protocatechuic aldehyde, ligustilide, and resveratrol were the most discriminated compounds in WS. The metabolic pathway analysis of differential metabolites related to the biosynthesis of flavonoids and phenolic acids were the biosynthesis of phenylpropanoids, flavonoids, isoflavonoids, flavones, and flavonols. This study substantially elucidated differences in the content of flavonoids and biological activities between WS and CS, which is useful information for the effective utilization of these two black soybean species in food processing. Full article

(This article belongs to the Section Phytochemistry)

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13 pages, 2293 KiB

Open AccessArticle

Genome-Wide Association Study Reveals the QTLs for Seed Storability in World Rice Core Collections

by Fangxi Wu, Xi Luo, Lingqiang Wang, Yidong Wei, Jianguo Li, Huaan Xie, Jianfu Zhang and Guosheng Xie

Plants 2021, 10(4), 812; https://doi.org/10.3390/plants10040812 - 20 Apr 2021

Cited by 12 | Viewed by 2876

Abstract

Seed storability is a main agronomically important trait to assure storage safety of grain and seeds in rice. Although many quantitative trait loci (QTLs) and associated genes for rice seed storability have been identified, the detailed genetic mechanisms of seed storability remain unclear [...] Read more.

Seed storability is a main agronomically important trait to assure storage safety of grain and seeds in rice. Although many quantitative trait loci (QTLs) and associated genes for rice seed storability have been identified, the detailed genetic mechanisms of seed storability remain unclear in rice. In this study, a genome-wide association study (GWAS) was performed in 456 diverse rice core collections from the 3K rice genome. We discovered the new nine QTLs designated as qSS1-1, qSS1-2, qSS2-1, qSS3-1, qSS5-1, qSS5-2, qSS7-1, qSS8-1, and qSS11-1. According to the analysis of the new nine QTLs, our results could well explain the reason why seed storability of indica subspecies was superior to japonica subspecies in rice. Among them, qSS1-2 and qSS8-1 were potentially co-localized with a known associated qSS1/OsGH3-2 and OsPIMT1, respectively. Our results also suggest that pyramiding breeding of superior alleles of these associated genes will lead to new varieties with improved seed storability in the future. Full article

(This article belongs to the Special Issue Genetic Diversity, Conservation, and Innovative Plant Breeding Strategies)

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17 pages, 310 KiB

Open AccessArticle

Effects of the Combinations of Rhizobacteria, Mycorrhizae, and Seaweed, and Supplementary Irrigation on Growth and Yield in Wheat Cultivars

by Z. Najafi Vafa, Y. Sohrabi, R. Z. Sayyed, Ni Luh Suriani and Rahul Datta

Plants 2021, 10(4), 811; https://doi.org/10.3390/plants10040811 - 20 Apr 2021

Cited by 37 | Viewed by 4120

Abstract

Wheat is a staple food consumed by the majority of people in the world and its production needs to be doubled to feed the growing population. On the other hand, global wheat productivity is greatly affected due to drought and low fertility of [...] Read more.

Wheat is a staple food consumed by the majority of people in the world and its production needs to be doubled to feed the growing population. On the other hand, global wheat productivity is greatly affected due to drought and low fertility of soil under arid and semi-arid regions. Application of supplementary irrigation and plant growth-promoting rhizobacteria (PGPR) has been suggested as sustainable measures to combat drought stress and to improve soil fertility and, hence, crop yield. This research was undertaken to study the effect of supplementary irrigation together with a combination of various PGPR on the growth and yield of two wheat cultivars, namely Sardari and Sirvan. The results of variance analysis (mean of squares) showed that the effect of irrigation, cultivar, and irrigation and biofertilizer and irrigation on height, spike length, seed/spike, and numbers of spikes/m², 1000-seed weight, and grain yield were significant at 1% probability level. The effect of cultivar and irrigation interactions showed that the highest grain yield was obtained in a treatment with two additional irrigations in Sirvan cultivar (5015.0 kg/ha) and Sardari (4838.9 kg/ha) as compared to the 3598 kg/ha and 3598.3 kg/h grain yield in Sirvan and Sardari cultivars with similar treatment, but without irrigation, i.e., dryland farming. Drought conditions significantly affected the wheat grain yield while supplementary irrigation resulted in 39.38% and 34.48% higher yields in Sirvan and Sardari cultivars. Full article

(This article belongs to the Section Plant Response to Abiotic Stress and Climate Change)

16 pages, 1146 KiB

Open AccessFeature PaperArticle

LED and HPS Supplementary Light Differentially Affect Gas Exchange in Tomato Leaves

by Onofrio Davide Palmitessa, Aina E. Prinzenberg, Elias Kaiser and Ep Heuvelink

Plants 2021, 10(4), 810; https://doi.org/10.3390/plants10040810 - 20 Apr 2021

Cited by 10 | Viewed by 3778

Abstract

Using light emitting diodes (LED) instead of conventionally used high pressure sodium (HPS) lamps as a supplemental light source in greenhouses results in a higher efficacy (µmol light per J electricity) and makes it possible to customize the light spectrum. To explore the [...] Read more.

Using light emitting diodes (LED) instead of conventionally used high pressure sodium (HPS) lamps as a supplemental light source in greenhouses results in a higher efficacy (µmol light per J electricity) and makes it possible to customize the light spectrum. To explore the effects of LED and HPS on gas exchange, thermal relations, photosynthesis, and water status of young tomato plants, seven genotypes were grown in a greenhouse under LED (95% red, 5% blue) or HPS lamps in four experiments differing in the fraction of lamp light over natural light. HPS lights emit a broader spectrum of red (40%), green–yellow (50%), blue (5%), and far-red (5%) and a substantial amount of infrared radiation (heat). Young tomato plants grown under LED showed lower leaf temperature and higher stomatal density, stomatal conductance (g_s) and transpiration rate (E) than plants grown under HPS; this may be due to the different supplemental light spectrum. The young plants grown under LED tended to have increased photosynthetic capacity. Furthermore, the water stress indices CWSI and I_G, which were obtained using thermal imaging, were positively correlated with gas exchange-derived g_s and E, putting forward the use of thermal imaging for the phenotyping of transpiration. Under LED light, photosynthetic gas exchange was generally increased, which agreed with the water stress indices. The extent of this increase was genotype-dependent. All differences between LED and HPS were smaller in the experiments where the fraction of lamp light over natural light was smaller. Full article

(This article belongs to the Special Issue Light and Plant Response: Adaptation to Extremes, Phenotypic Plasticity and Plant Competition)

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12 pages, 3138 KiB

Open AccessCommunication

Shade Avoidance and Light Foraging of a Clonal Woody Species, Pachysandra terminalis

by Risa Iwabe, Kohei Koyama and Riko Komamura

Plants 2021, 10(4), 809; https://doi.org/10.3390/plants10040809 - 20 Apr 2021

Cited by 9 | Viewed by 3111

Abstract

(1) Background: A central subject in clonal plant ecology is to elucidate the mechanism by which clones forage resources in heterogeneous environments. Compared with studies conducted in laboratories or experimental gardens, studies on light foraging of forest woody clonal plants in their natural [...] Read more.

(1) Background: A central subject in clonal plant ecology is to elucidate the mechanism by which clones forage resources in heterogeneous environments. Compared with studies conducted in laboratories or experimental gardens, studies on light foraging of forest woody clonal plants in their natural habitats are limited. (2) Methods: We investigated wild populations of an evergreen clonal understory shrub, Japanese pachysandra (Pachysandra terminalis Siebold & Zucc.), in two cool-temperate forests in Japan. (3) Results: Similar to the results of herbaceous clonal species, this species formed a dense stand in a relatively well-lit place, and a sparse stand in a shaded place. Higher specific rhizome length (i.e., length per unit mass) in shade resulted in lower ramet population density in shade. The individual leaf area, whole-ramet leaf area, or ramet height did not increase with increased light availability. The number of flower buds per flowering ramet increased as the canopy openness or population density increased. (4) Conclusions: Our results provide the first empirical evidence of shade avoidance and light foraging with morphological plasticity for a clonal woody species. Full article

(This article belongs to the Section Plant Ecology)

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19 pages, 4842 KiB

Open AccessArticle

Morpho-Physiological, Biochemical, and Genetic Responses to Salinity in Medicago truncatula

by Sabrine Hdira, Loua Haddoudi, Mohsen Hanana, Irene Romero, Asma Mahjoub, Hatem Ben Jouira, Ndiko Ludidi, Maria Teresa Sanchez-Ballesta, Chedly Abdelly and Mounawer Badri

Plants 2021, 10(4), 808; https://doi.org/10.3390/plants10040808 - 20 Apr 2021

Cited by 6 | Viewed by 3027

Abstract

We used an integrated morpho-physiological, biochemical, and genetic approach to investigate the salt responses of four lines (TN1.11, TN6.18, JA17, and A10) of Medicago truncatula. Results showed that TN1.11 exhibited a high tolerance to salinity, compared with the other lines, recording a [...] Read more.

We used an integrated morpho-physiological, biochemical, and genetic approach to investigate the salt responses of four lines (TN1.11, TN6.18, JA17, and A10) of Medicago truncatula. Results showed that TN1.11 exhibited a high tolerance to salinity, compared with the other lines, recording a salinity induced an increase in soluble sugars and soluble proteins, a slight decrease in malondialdehyde (MDA) accumulation, and less reduction in plant biomass. TN6.18 was the most susceptible to salinity as it showed less plant weight, had elevated levels of MDA, and lower levels of soluble sugars and soluble proteins under salt stress. As transcription factors of the APETALA2/ethylene responsive factor (AP2/ERF) family play important roles in plant growth, development, and responses to biotic and abiotic stresses, we performed a functional characterization of MtERF1 gene. Real-time PCR analysis revealed that MtERF1 is mainly expressed in roots and is inducible by NaCl and low temperature. Additionally, under salt stress, a greater increase in the expression of MtERF1 was found in TN1.11 plants than that in TN6.18. Therefore, the MtERF1 pattern of expression may provide a useful marker for discriminating among lines of M. truncatula and can be used as a tool in breeding programs aiming at obtaining Medicago lines with improved salt tolerance. Full article

(This article belongs to the Special Issue Molecular Analysis of Medicago Spp.)

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24 pages, 811 KiB

Open AccessReview

Advances in Understanding of Desiccation Tolerance of Lichens and Lichen-Forming Algae

by Francisco Gasulla, Eva M del Campo, Leonardo M. Casano and Alfredo Guéra

Plants 2021, 10(4), 807; https://doi.org/10.3390/plants10040807 - 20 Apr 2021

Cited by 40 | Viewed by 6009

Abstract

Lichens are symbiotic associations (holobionts) established between fungi (mycobionts) and certain groups of cyanobacteria or unicellular green algae (photobionts). This symbiotic association has been essential in the colonization of terrestrial dry habitats. Lichens possess key mechanisms involved in desiccation tolerance (DT) that are [...] Read more.

Lichens are symbiotic associations (holobionts) established between fungi (mycobionts) and certain groups of cyanobacteria or unicellular green algae (photobionts). This symbiotic association has been essential in the colonization of terrestrial dry habitats. Lichens possess key mechanisms involved in desiccation tolerance (DT) that are constitutively present such as high amounts of polyols, LEA proteins, HSPs, a powerful antioxidant system, thylakoidal oligogalactolipids, etc. This strategy allows them to be always ready to survive drastic changes in their water content. However, several studies indicate that at least some protective mechanisms require a minimal time to be induced, such as the induction of the antioxidant system, the activation of non-photochemical quenching including the de-epoxidation of violaxanthin to zeaxanthin, lipid membrane remodeling, changes in the proportions of polyols, ultrastructural changes, marked polysaccharide remodeling of the cell wall, etc. Although DT in lichens is achieved mainly through constitutive mechanisms, the induction of protection mechanisms might allow them to face desiccation stress in a better condition. The proportion and relevance of constitutive and inducible DT mechanisms seem to be related to the ecology at which lichens are adapted to. Full article

(This article belongs to the Special Issue Water Stress and Desiccation Tolerance in Plants)

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12 pages, 1805 KiB

Open AccessArticle

Analysis of Cadmium Root Retention for Two Contrasting Rice Accessions Suggests an Important Role for OsHMA2

by Moez Maghrebi, Elena Baldoni, Giorgio Lucchini, Gianpiero Vigani, Giampiero Valè, Gian Attilio Sacchi and Fabio Francesco Nocito

Plants 2021, 10(4), 806; https://doi.org/10.3390/plants10040806 - 20 Apr 2021

Cited by 13 | Viewed by 2770

Abstract

Two rice accessions, Capataz and Beirao, contrasting for cadmium (Cd) tolerance and root retention, were exposed to a broad range of Cd concentrations (0.01, 0.1, and 1 μM) and analyzed for their potential capacity to chelate, compartmentalize, and translocate Cd to gain information [...] Read more.

Two rice accessions, Capataz and Beirao, contrasting for cadmium (Cd) tolerance and root retention, were exposed to a broad range of Cd concentrations (0.01, 0.1, and 1 μM) and analyzed for their potential capacity to chelate, compartmentalize, and translocate Cd to gain information about the relative contribution of these processes in determining the different pathways of Cd distribution along the plants. In Capataz, Cd root retention increased with the external Cd concentration, while in Beirao it resulted independent of Cd availability and significantly higher than in Capataz at the lowest Cd concentrations analyzed. Analysis of thiol accumulation in the roots revealed that the different amounts of these compounds in Capataz and Beirao, as well as the expression levels of genes involved in phytochelatin biosynthesis and direct Cd sequestration into the vacuoles of the root cells, were not related to the capacity of the accessions to trap the metal into the roots. Interestingly, the relative transcript abundance of OsHMA2, a gene controlling root-to-shoot Cd/Zn translocation, was not influenced by Cd exposure in Capataz and progressively increased in Beirao with the external Cd concentration, suggesting that activity of the OsHMA2 transporter may differentially limit root-to-shoot Cd/Zn translocation in Capataz and Beirao. Full article

(This article belongs to the Section Plant Nutrition)

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17 pages, 3669 KiB

Open AccessArticle

Investigating the Invasion Pattern of the Alien Plant Solanum elaeagnifolium Cav. (Silverleaf Nightshade): Environmental and Human-Induced Drivers

by Nikos Krigas, Maria A. Tsiafouli, Georgios Katsoulis, Nefta-Eleftheria Votsi and Mark van Kleunen

Plants 2021, 10(4), 805; https://doi.org/10.3390/plants10040805 - 20 Apr 2021

Cited by 26 | Viewed by 4302

Abstract

Invasive alien plant species have impacts on nature conservation, ecosystem services and agricultural production. To identify environmental and human-related drivers of the invasion of Solanum elaeagnifolium (Solanaceae)—one of the worst alien invasive plants worldwide—we conducted an extensive drive-by survey across the Greek territory [...] Read more.

Invasive alien plant species have impacts on nature conservation, ecosystem services and agricultural production. To identify environmental and human-related drivers of the invasion of Solanum elaeagnifolium (Solanaceae)—one of the worst alien invasive plants worldwide—we conducted an extensive drive-by survey across the Greek territory (presence/absence data; all national major multilane highways; 12–25% of the remaining road network; driven 3–5 times during 2000–2020). These data were linked in GIS with (i) physical environmental attributes (elevation, climate, soil properties) and (ii) type and intensity of human-related activities (land uses, settlements and road type). Compared to previous records, our survey showed that the range of S. elaeagnifolium increased by 1750% during the last decades, doubling its main distribution centers and reaching higher elevations. Our study revealed that the presence of S. elaeagnifolium is associated with (i) higher maximum temperatures and precipitation in summer and low precipitation in winter, as well as with (ii) soil disturbance related to agricultural activities, settlements and road networks, thus facilitating its spread mainly at low altitudes. Our study elucidates the current invasion pattern of S. elaeagnifolium and highlights the urgent need for its widespread monitoring, at least in the noninvaded areas in Greece that have been surveyed in this study. Preventative measures and integrative initiatives should be implemented quickly, and urgently incorporated into current agricultural, road network and conservation-management regimes. Full article

(This article belongs to the Special Issue Super-Weeds: Knowledge of Their Biology, Physiology and Ecology Will Alleviate Their Effects on Crops and Enhance Management Options for Long-Term Control)

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18 pages, 3131 KiB

Open AccessEditor’s ChoiceArticle

Breeding of High Cooking and Eating Quality in Rice by Marker-Assisted Backcrossing (MABc) Using KASP Markers

by Me-Sun Kim, Ju-Young Yang, Ju-Kyung Yu, Yi Lee, Yong-Jin Park, Kwon-Kyoo Kang and Yong-Gu Cho

Plants 2021, 10(4), 804; https://doi.org/10.3390/plants10040804 - 19 Apr 2021

Cited by 20 | Viewed by 4141

Abstract

The primary goals of rice breeding programs are grain quality and yield potential improvement. With the high demand for rice varieties of premium cooking and eating quality, we developed low-amylose content breeding lines crossed with Samgwang and Milkyqueen through the marker-assisted backcross (MABc) [...] Read more.

The primary goals of rice breeding programs are grain quality and yield potential improvement. With the high demand for rice varieties of premium cooking and eating quality, we developed low-amylose content breeding lines crossed with Samgwang and Milkyqueen through the marker-assisted backcross (MABc) breeding program. Trait markers of the SSIIIa gene referring to low-amylose content were identified through an SNP mapping activity, and the markers were applied to select favorable lines for a foreground selection. To rapidly recover the genetic background of Samgwang (recurrent parent genome, RPG), 386 genome-wide markers were used to select BC₁F₁ and BC₂F₁ individuals. Seven BC₂F₁ lines with targeted traits were selected, and the genetic background recovery range varied within 97.4–99.1% of RPG. The amylose content of the selected BC₂F₂ grains ranged from 12.4–16.8%. We demonstrated the MABc using a trait and genome-wide markers, allowing us to efficiently select lines of a target trait and reduce the breeding cycle effectively. In addition, the BC₂F₂ lines confirmed by molecular markers in this study can be utilized as parental lines for subsequent breeding programs of high-quality rice for cooking and eating. Full article

(This article belongs to the Special Issue Functional Analysis of Starch Metabolism in Plants)

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12 pages, 1354 KiB

Open AccessArticle

Aromatic Profile Variation of Essential Oil from Dried Makwhaen Fruit and Related Species

by Trid Sriwichai, Jiratchaya Wisetkomolmat, Tonapha Pusadee, Korawan Sringarm, Kiattisak Duangmal, Shashanka K. Prasad, Bajaree Chuttong and Sarana Rose Sommano

Plants 2021, 10(4), 803; https://doi.org/10.3390/plants10040803 - 19 Apr 2021

Cited by 8 | Viewed by 3103

Abstract

The aim of this research is to evaluate the relationship between genotype, phenotype, and chemical profiles of essential oil obtained from available Zanthoxylum spp. Three specimens of makhwaen (MK) distributed in Northern Thailand were genetically and morphologically compared with other Zanthoxylum spices, known [...] Read more.

The aim of this research is to evaluate the relationship between genotype, phenotype, and chemical profiles of essential oil obtained from available Zanthoxylum spp. Three specimens of makhwaen (MK) distributed in Northern Thailand were genetically and morphologically compared with other Zanthoxylum spices, known locally as huajiao (HJ) and makwoung (MKO), respectively. HJ was taxonomically confirmed as Z. armatum while MKO and MK were identified as Z. rhetsa and Z. myriacanthum. Genetic sequencing distributed these species into three groups accordingly to their confirmed species. Essential oil of the dried fruits from these samples was extracted and analyzed for their chemical and physical properties. Cluster analysis of their volatile compositions separated MKO and MK apart from HJ with L-limonene, terpinen-4-ol, β-phellandrene, and β-philandrene. By using odor attributes, the essential oil of MKO and MK were closely related possessing fruity, woody, and citrus aromas, while the HJ was distinctive. Overall, the phenotypic characteristic can be used to elucidate the species among makhwaen fruits of different sources. The volatile profiling was nonetheless dependent on the genotypes but makwoung and makhwaen showed similar profiles. Full article

(This article belongs to the Special Issue Spicy and Aromatic Plants)

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17 pages, 2961 KiB

Open AccessArticle

Production of Phytotoxic Metabolites by Botryosphaeriaceae in Naturally Infected and Artificially Inoculated Grapevines

by Pierluigi Reveglia, Regina Billones-Baaijens, Jennifer Millera Niem, Marco Masi, Alessio Cimmino, Antonio Evidente and Sandra Savocchia

Plants 2021, 10(4), 802; https://doi.org/10.3390/plants10040802 - 19 Apr 2021

Cited by 10 | Viewed by 3166

Abstract

Grapevine trunk diseases (GTDs) are considered a serious problem to viticulture worldwide. Several GTD fungal pathogens produce phytotoxic metabolites (PMs) that were hypothesized to migrate to the foliage where they cause distinct symptoms. The role of PMs in the expression of Botryosphaeria dieback [...] Read more.

Grapevine trunk diseases (GTDs) are considered a serious problem to viticulture worldwide. Several GTD fungal pathogens produce phytotoxic metabolites (PMs) that were hypothesized to migrate to the foliage where they cause distinct symptoms. The role of PMs in the expression of Botryosphaeria dieback (BD) symptoms in naturally infected and artificially inoculated wood using molecular and analytical chemistry techniques was investigated. Wood samples from field vines naturally infected with BD and one-year-old vines inoculated with Diplodia seriata, Spencermartinsia viticola and Dothiorella vidmadera were analysed by cultural isolations, quantitative PCR (qPCR) and targeted LC-MS/MS to detect three PMs: (R)-mellein, protocatechuic acid and spencertoxin. (R)-mellein was detected in symptomatic naturally infected wood and vines artificially inoculated with D. seriata but was absent in all non-symptomatic wood. The amount of (R)-mellein detected was correlated with the amount of pathogen DNA detected by qPCR. Protocatechuic acid and spencertoxin were absent in all inoculated wood samples. (R)-mellein may be produced by the pathogen during infection to break down the wood, however it was not translocated into other parts of the vine. The foliar symptoms previously reported in vineyards may be due to a combination of PMs produced and climatic and physiological factors that require further investigation. Full article

(This article belongs to the Special Issue Decline of Mediterranean Fruit Crops and Forests Associated with Fungal Trunk Pathogens)

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20 pages, 1993 KiB

Open AccessEditor’s ChoiceArticle

Effect of Different Ratios of Blue and Red LED Light on Brassicaceae Microgreens under a Controlled Environment

by Aušra Brazaitytė, Jurga Miliauskienė, Viktorija Vaštakaitė-Kairienė, Rūta Sutulienė, Kristina Laužikė, Pavelas Duchovskis and Stanisław Małek

Plants 2021, 10(4), 801; https://doi.org/10.3390/plants10040801 - 19 Apr 2021

Cited by 68 | Viewed by 9137

Abstract

The consumption of microgreens has increased due to their having higher levels of bioactive compounds and mineral nutrients than mature plants. The lighting conditions during the cultivation of microgreens, if optimally selected, can have a positive effect by further increasing their nutritional value. [...] Read more.

The consumption of microgreens has increased due to their having higher levels of bioactive compounds and mineral nutrients than mature plants. The lighting conditions during the cultivation of microgreens, if optimally selected, can have a positive effect by further increasing their nutritional value. Thus, our study aimed to determine the changes in mineral nutrients contents of Brassicaceae microgreens depending on different blue–red (B:R) light ratios in light-emitting diode (LED) lighting and to evaluate their growth and nutritional value according to different indexes. Experiments were performed in controlled environment growth chambers at IH LRCAF, 2020. Microgreens of mustard (Brassica juncea ‘Red Lace’) and kale (Brassica napus ‘Red Russian’) were grown hydroponically under different B:R light ratios: 0%B:100%R, 10%B:90%R, 25%B:75%R, 50%B:50%R, 75%B:25%R, and 100%B:0%R. A 220 μmol m⁻² s⁻¹ total photon flux density (TPFD), 18 h photoperiod, 21/17 ± 2 °C temperature and 60% ± 5% relative humidity in the growth chamber were maintained during cultivation. We observed that an increasing percentage of blue light in the LED illumination spectrum during growth was associated with reduced elongation in the microgreens of both species and had a positive effect on the accumulation of mostly macro- and micronutrients. However, different B:R light ratios indicate a species-dependent response to changes in growth parameters such as leaf area, fresh and dry mass, and optical leaf indexes such as for chlorophyll, flavonol, anthocyanin, and carotenoid reflectance. Full article

(This article belongs to the Special Issue Applications and Advances in Artificial Light for Horticulture and Crop Production)

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27 pages, 3229 KiB

Open AccessArticle

Intraspecific Variation in Nickel Tolerance and Hyperaccumulation among Serpentine and Limestone Populations of Odontarrhena serpyllifolia (Brassicaceae: Alysseae) from the Iberian Peninsula

by A. Joseph Pollard, Grace L. McCartha, Celestino Quintela-Sabarís, Thomas A. Flynn, Maria K. Sobczyk and J. Andrew C. Smith

Plants 2021, 10(4), 800; https://doi.org/10.3390/plants10040800 - 19 Apr 2021

Cited by 4 | Viewed by 3272

Abstract

Odontarrhena serpyllifolia (Desf.) Jord. & Fourr. (=Alyssum serpyllifolium Desf.) occurs in the Iberian Peninsula and adjacent areas on a variety of soils including both limestone and serpentine (ultramafic) substrates. Populations endemic to serpentine are known to hyperaccumulate nickel, and on account of [...] Read more.

Odontarrhena serpyllifolia (Desf.) Jord. & Fourr. (=Alyssum serpyllifolium Desf.) occurs in the Iberian Peninsula and adjacent areas on a variety of soils including both limestone and serpentine (ultramafic) substrates. Populations endemic to serpentine are known to hyperaccumulate nickel, and on account of this remarkable phenotype have, at times, been proposed for recognition as taxonomically distinct subspecies or even species. It remains unclear, however, to what extent variation in nickel hyperaccumulation within this taxon merely reflects differences in the substrate, or whether the different populations show local adaptation to their particular habitats. To help clarify the physiological basis of variation in nickel hyperaccumulation among these populations, 3 serpentine accessions and 3 limestone accessions were cultivated hydroponically under common-garden conditions incorporating a range of Ni concentrations, along with 2 closely related non-accumulator species, Clypeola jonthlaspi L. and Alyssum montanum L. As a group, serpentine accessions of O. serpyllifolia were able to tolerate Ni concentrations approximately 10-fold higher than limestone accessions, but a continuous spectrum of Ni tolerance was observed among populations, with the least tolerant serpentine accession not being significantly different from the most tolerant limestone accession. Serpentine accessions maintained relatively constant tissue concentrations of Ca, Mg, K, and Fe across the whole range of Ni exposures, whereas in the limestone accessions, these elements fluctuated widely in response to Ni toxicity. Hyperaccumulation of Ni, defined here as foliar Ni concentrations exceeding 1g kg⁻¹ of dry biomass in plants not showing significant growth reduction, occurred in all accessions of O. serpyllifolia, but the higher Ni tolerance of serpentine accessions allowed them to hyperaccumulate more strongly. Of the reference species, C. jonthlaspi responded similarly to the limestone accessions of O. serpyllifolia, whereas A. montanum displayed by far the lowest degree of Ni tolerance and exhibited low foliar Ni concentrations, which only exceeded 1 g kg⁻¹ in plants showing severe Ni toxicity. The continuous spectrum of physiological responses among these accessions does not lend support to segregation of the serpentine populations of O. serpyllifolia as distinct species. However, the pronounced differences in degrees of Ni tolerance, hyperaccumulation, and elemental homeostasis observed among these accessions under common-garden conditions argues for the existence of population-level adaptation to their local substrates. Full article

(This article belongs to the Special Issue Metallophytes)

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17 pages, 2532 KiB

Open AccessArticle

Effects of Monochromatic Illumination with LEDs Lights on the Growth and Photosynthetic Performance of Auxenochlorella protothecoides in Photo- and Mixotrophic Conditions

by Giorgos Markou, Alexandros Diamantis, Evagelina Korozi, Vasiliki Tsagou, Io Kefalogianni and Iordanis Chatzipavlidis

Plants 2021, 10(4), 799; https://doi.org/10.3390/plants10040799 - 19 Apr 2021

Cited by 9 | Viewed by 2854

Abstract

This study examined the effects of monochromatic illumination (blue, red, green and yellow) employing light-emitting diodes (LEDs), trophic conditions (photoautotrophic and mixotrophic), and nitrogen availability (high and low peptone concentration) on the growth and biochemical composition of Auxenochlorella protothecoides. The results revealed [...] Read more.

This study examined the effects of monochromatic illumination (blue, red, green and yellow) employing light-emitting diodes (LEDs), trophic conditions (photoautotrophic and mixotrophic), and nitrogen availability (high and low peptone concentration) on the growth and biochemical composition of Auxenochlorella protothecoides. The results revealed that mixotrophic conditions did not favor A. protothecoides, giving lower growth rates compared to heterotrophy (dark conditions). However, mixotrophy gave significantly higher growth rates compared to photoautotrophy. The best light wavelengths for mixotrophic cultivation were that of white and red. In all cases investigated in this study, high peptone concentration (4 g/L) resulted in decreased growth rates. Regarding the biochemical composition of A. protothecoides, the strongest effect, irrespective of trophic conditions, was caused by nitrogen availability (peptone concentration). Specifically, at nitrogen replete conditions (4 g/L peptone), biomass was rich in proteins (32–67%), whereas under deplete conditions (0.5 g/L peptone), A. protothecoides accumulated mainly carbohydrates (up to 56%). Mixotrophic conditions generally favored higher carbohydrate content, whereas photoautotrophic conditions favored higher protein content. The different illumination spectra did not have any clear effect on the biochemical composition (metabolites content), except that, in all trophic conditions, the use of the green spectrum resulted in higher chlorophyll b content. Chlorophyll a fluorescence studies revealed that the trophic conditions and the high peptone concentrations impacted the photosystem II (PSII) performance, and also affected plastoquinone re-oxidation kinetics and the heterogeneity of the PSII reaction centers. Full article

(This article belongs to the Special Issue Algal Biomass)

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18 pages, 3445 KiB

Open AccessArticle

Genome-Wide Association Study of Local Thai Indica Rice Seedlings Exposed to Excessive Iron

by Reunreudee Kaewcheenchai, Phanchita Vejchasarn, Kousuke Hanada, Kazumasa Shirai, Chatchawan Jantasuriyarat and Piyada Juntawong

Plants 2021, 10(4), 798; https://doi.org/10.3390/plants10040798 - 19 Apr 2021

Cited by 5 | Viewed by 3825

Abstract

Excess soluble iron in acidic soil is an unfavorable environment that can reduce rice production. To better understand the tolerance mechanism and identify genetic loci associated with iron toxicity (FT) tolerance in a highly diverse indica Thai rice population, a genome-wide association study [...] Read more.

Excess soluble iron in acidic soil is an unfavorable environment that can reduce rice production. To better understand the tolerance mechanism and identify genetic loci associated with iron toxicity (FT) tolerance in a highly diverse indica Thai rice population, a genome-wide association study (GWAS) was performed using genotyping by sequencing and six phenotypic data (leaf bronzing score (LBS), chlorophyll content, shoot height, root length, shoot biomass, and root dry weight) under both normal and FT conditions. LBS showed a high negative correlation with the ratio of chlorophyll content and shoot biomass, indicating the FT-tolerant accessions can regulate cellular homeostasis when encountering stress. Sixteen significant single nucleotide polymorphisms (SNPs) were identified by association mapping. Validation of candidate SNP using other FT-tolerant accessions revealed that SNP:2_21262165 might be associated with tolerance to FT; therefore, it could be used for SNP marker development. Among the candidate genes controlling FT tolerance, RAR1 encodes an innate immune responsive protein that links to cellular redox homeostasis via interacting with abiotic stress-responsive Hsp90. Future research may apply the knowledge obtained from this study in the molecular breeding program to develop FT-tolerant rice varieties. Full article

(This article belongs to the Special Issue Genomics, Genetics, and Breeding for Rice Crop Improvement)

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17 pages, 3818 KiB

Open AccessArticle

Magnesium Foliar Supplementation Increases Grain Yield of Soybean and Maize by Improving Photosynthetic Carbon Metabolism and Antioxidant Metabolism

by Vitor Alves Rodrigues, Carlos Alexandre Costa Crusciol, João William Bossolani, Luiz Gustavo Moretti, José Roberto Portugal, Tamara Thaís Mundt, Sirlene Lopes de Oliveira, Ariani Garcia, Juliano Carlos Calonego and Romulo Pisa Lollato

Plants 2021, 10(4), 797; https://doi.org/10.3390/plants10040797 - 19 Apr 2021

Cited by 25 | Viewed by 6634

Abstract

(1) Background: The aim of this study was to explore whether supplementary magnesium (Mg) foliar fertilization to soybean and maize crops established in a soil without Mg limitation can improve the gas exchange and Rubisco activity, as well as improve antioxidant metabolism, converting [...] Read more.

(1) Background: The aim of this study was to explore whether supplementary magnesium (Mg) foliar fertilization to soybean and maize crops established in a soil without Mg limitation can improve the gas exchange and Rubisco activity, as well as improve antioxidant metabolism, converting higher plant metabolism into grain yield. (2) Methods: Here, we tested foliar Mg supplementation in soybean followed by maize. Nutritional status of plants, photosynthesis, PEPcase and Rubisco activity, sugar concentration on leaves, oxidative stress, antioxidant metabolism, and finally the crops grain yields were determined. (3) Results: Our results demonstrated that foliar Mg supplementation increased the net photosynthetic rate and stomatal conductance, and reduced the sub-stomatal CO₂ concentration and leaf transpiration by measuring in light-saturated conditions. The improvement in photosynthesis (gas exchange and Rubisco activity) lead to an increase in the concentration of sugar in the leaves before grain filling. In addition, we also confirmed that foliar Mg fertilization can improve anti-oxidant metabolism, thereby reducing the environmental stress that plants face during their crop cycle in tropical field conditions. (4) Conclusions: Our research brings the new glimpse of foliar Mg fertilization as a strategy to increase the metabolism of crops, resulting in increased grain yields. This type of biological strategy could be encouraged for wide utilization in cropping systems. Full article

(This article belongs to the Section Plant Nutrition)

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17 pages, 765 KiB

Open AccessArticle

Ameliorative Effects of Exogenous Proline on Photosynthetic Attributes, Nutrients Uptake, and Oxidative Stresses under Cadmium in Pigeon Pea (Cajanus cajan L.)

by Khizar Hayat, Jafar Khan, Asif Khan, Shakir Ullah, Shahid Ali, Salahuddin and Yujie Fu

Plants 2021, 10(4), 796; https://doi.org/10.3390/plants10040796 - 19 Apr 2021

Cited by 44 | Viewed by 4190

Abstract

Proline plays a significant role in the plant response to stress conditions. However, its role in alleviating metal-induced stresses remains elusive. We conducted an experiment to evaluate the ameliorative role of exogenous proline on cadmium-induced inhibitory effects in pigeon pea subjected to different [...] Read more.

Proline plays a significant role in the plant response to stress conditions. However, its role in alleviating metal-induced stresses remains elusive. We conducted an experiment to evaluate the ameliorative role of exogenous proline on cadmium-induced inhibitory effects in pigeon pea subjected to different Cd treatments (4 and 8 mg/mL). Cadmium treatments reduced photosynthetic attributes, decreased chlorophyll contents, disturbed nutrient uptake, and affected growth traits. The elevated activity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), in association with relatively high contents of hydrogen peroxide, thiobarbituric acid reactive substances, electrolyte leakage, and endogenous proline, was measured. Exogenous proline application (3 and 6 mM) alleviated cadmium-induced oxidative damage. Exogenous proline increased antioxidant enzyme activities and improved photosynthetic attributes, nutrient uptake (Mg²⁺, Ca²⁺, K⁺), and growth parameters in cadmium-stressed pigeon pea plants. Our results reveal that proline supplementation can comprehensively alleviate the harmful effects of cadmium on pigeon pea plants. Full article

(This article belongs to the Special Issue Heavy Metal Stress in Plants)

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12 pages, 2206 KiB

Open AccessArticle

Optimized Protocol for In Vitro Pollen Germination in Yam (Dioscorea spp.)

by Jean M. Mondo, Paterne A. Agre, Robert Asiedu, Malachy O. Akoroda and Asrat Asfaw

Plants 2021, 10(4), 795; https://doi.org/10.3390/plants10040795 - 18 Apr 2021

Cited by 14 | Viewed by 3349

Abstract

Yam (Dioscorea spp.) plants are mostly dioecious and sometimes monoecious. Low, irregular, and asynchronous flowering of the genotypes are critical problems in yam breeding. Selecting suitable pollen parents and preserving yam pollen for future use are potential means of controlling these constraints [...] Read more.

Yam (Dioscorea spp.) plants are mostly dioecious and sometimes monoecious. Low, irregular, and asynchronous flowering of the genotypes are critical problems in yam breeding. Selecting suitable pollen parents and preserving yam pollen for future use are potential means of controlling these constraints and optimizing hybridization practice in yam breeding programs. However, implementing such procedures requires a robust protocol for pollen collection and viability testing to monitor pollen quality in the field and in storage. This study, therefore, aimed at optimizing the pollen germination assessment protocol for yam. The standard medium composition was stepwisely modified, the optimal growth condition was tested, and in vivo predictions were made. This study showed that the differences in yam pollen germination percentage are primarily linked to the genotype and growing conditions (i.e., medium viscosity, incubation temperature, and time to use) rather than the medium composition. The inclusion of polyethylene glycol (PEG) in the culture medium caused 67–75% inhibition of germination in D. alata. Although the in vivo fertilization was dependent on female parents, the in vitro germination test predicted the percentage fruit set at 25.2–79.7% and 26.4–59.7% accuracy for D. rotundata and D. alata genotypes, respectively. This study provides a reliable in vitro yam pollen germination protocol to support pollen management and preservation efforts in yam breeding. Full article

(This article belongs to the Special Issue Floral Biology)

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15 pages, 1034 KiB

Open AccessArticle

Inhibitory Effects of Brassicaceae Cover Crop on Ambrosia artemisiifolia Germination and Early Growth

by Maja Šćepanović, Marija Sarić-Krsmanović, Valentina Šoštarčić, Ema Brijačak, Josip Lakić, Bojana Špirović Trifunović, Jelena Gajić Umiljendić and Ljiljana Radivojević

Plants 2021, 10(4), 794; https://doi.org/10.3390/plants10040794 - 17 Apr 2021

Cited by 8 | Viewed by 2517

Abstract

Several cover crops (CCs) exert allelopathic effects that suppress weed growth. The aim of the present study was to evaluate the effects of aqueous extracts containing different concentrations [0, 0.5, 1, 2.5, 5, 7.5 and 10% (w/v)] of Brassicaceae [...] Read more.

Several cover crops (CCs) exert allelopathic effects that suppress weed growth. The aim of the present study was to evaluate the effects of aqueous extracts containing different concentrations [0, 0.5, 1, 2.5, 5, 7.5 and 10% (w/v)] of Brassicaceae CCs (Sinapis alba, Raphanus sativus, Camellina sativa) and of the CCs Fagopyrum esculentum and Guizotia abyssinica on germination and early growth of Ambrosia artemisiifolia L. The allelopathic effects were species and concentration-dependent. C. sativa, for example, caused the greatest potential to inhibit germination, shoot, radicle length and fresh seedling weight, whereas S. alba and R. sativus inhibited germination and early growth of A. artemisiifolia only at concentrations ≥7.5%. In contrast, no inhibition was observed when aqueous extracts of F. escultneum and G. abyssinica were added at any of tested concentration. Liquid chromatography-tandem mass spectrometry detected 15 phenolic compounds in Brassicaceae CCs with the highest content (µg/g) of vanillin (48.8), chlorogenic acid (1057), vanilic acid (79), caffeic acid (102.5) and syringic acid (27.3) in C. sativa. Our results suggest that C. sativa is the most allelopathic CCs and that the fruits of C. sativa are the plant organs richest in allelochemicals. Full article

(This article belongs to the Special Issue Super-Weeds: Knowledge of Their Biology, Physiology and Ecology Will Alleviate Their Effects on Crops and Enhance Management Options for Long-Term Control)

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24 pages, 3392 KiB

Open AccessArticle

Differential Epigenetic Marks Are Associated with Apospory Expressivity in Diploid Hybrids of Paspalum rufum

by Mariano Soliman, Maricel Podio, Gianpiero Marconi, Marco Di Marsico, Juan Pablo A. Ortiz, Emidio Albertini and Luciana Delgado

Plants 2021, 10(4), 793; https://doi.org/10.3390/plants10040793 - 17 Apr 2021

Cited by 6 | Viewed by 2947

Abstract

Apomixis seems to emerge from the deregulation of preexisting genes involved in sexuality by genetic and/or epigenetic mechanisms. The trait is associated with polyploidy, but diploid individuals of Paspalum rufum can form aposporous embryo sacs and develop clonal seeds. Moreover, diploid hybrid families [...] Read more.

Apomixis seems to emerge from the deregulation of preexisting genes involved in sexuality by genetic and/or epigenetic mechanisms. The trait is associated with polyploidy, but diploid individuals of Paspalum rufum can form aposporous embryo sacs and develop clonal seeds. Moreover, diploid hybrid families presented a wide apospory expressivity variation. To locate methylation changes associated with apomixis expressivity, we compare relative DNA methylation levels, at CG, CHG, and CHH contexts, between full-sib P. rufum diploid genotypes presenting differential apospory expressivity. The survey was performed using a methylation content-sensitive enzyme ddRAD (MCSeEd) strategy on samples at premeiosis/meiosis and postmeiosis stages. Based on the relative methylation level, principal component analysis and heatmaps, clearly discriminate samples with contrasting apospory expressivity. Differential methylated contigs (DMCs) showed 14% of homology to known transcripts of Paspalum notatum reproductive transcriptome, and almost half of them were also differentially expressed between apomictic and sexual samples. DMCs showed homologies to genes involved in flower growth, development, and apomixis. Moreover, a high proportion of DMCs aligned on genomic regions associated with apomixis in Setaria italica. Several stage-specific differential methylated sequences were identified as associated with apospory expressivity, which could guide future functional gene characterization in relation to apomixis success at diploid and tetraploid levels. Full article

(This article belongs to the Special Issue DNA Methylation in Plants)

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17 pages, 1094 KiB

Open AccessArticle

Biochemical and Proteomic Changes in the Roots of M4 Grapevine Rootstock in Response to Nitrate Availability

by Bhakti Prinsi, Chiara Muratore and Luca Espen

Plants 2021, 10(4), 792; https://doi.org/10.3390/plants10040792 - 17 Apr 2021

Cited by 1 | Viewed by 2396

Abstract

In agricultural soils, nitrate (NO₃⁻) is the major nitrogen (N) nutrient for plants, but few studies have analyzed molecular and biochemical responses involved in its acquisition by grapevine roots. In viticulture, considering grafting, NO₃⁻ acquisition is strictly dependent [...] Read more.

In agricultural soils, nitrate (NO₃⁻) is the major nitrogen (N) nutrient for plants, but few studies have analyzed molecular and biochemical responses involved in its acquisition by grapevine roots. In viticulture, considering grafting, NO₃⁻ acquisition is strictly dependent on rootstock. To improve the knowledge about N nutrition in grapevine, this study analyzed biochemical and proteomic changes induced by, NO₃⁻ availability, in a hydroponic system, in the roots of M4, a recently selected grapevine rootstock. The evaluation of biochemical parameters, such as NO₃⁻, sugar and amino acid contents in roots, and the abundance of nitrate reductase, allowed us to define the time course of the metabolic adaptations to NO₃⁻ supply. On the basis of these results, the proteomic analysis was conducted by comparing the root profiles in N-starved plants and after 30 h of NO₃⁻ resupply. The analysis quantified 461 proteins, 26% of which differed in abundance between conditions. Overall, this approach highlighted, together with an increased N assimilatory metabolism, a concomitant rise in the oxidative pentose phosphate pathway and glycolysis, needed to fulfill the redox power and carbon skeleton demands, respectively. Moreover, a wide modulation of protein and amino acid metabolisms and changes of proteins involved in root development were observed. Finally, some results open new questions about the importance of redox-related post-translational modifications and of NO₃⁻ availability in modulating the dialog between root and rhizosphere. Full article

(This article belongs to the Special Issue Omic Sciences in the Fields of Crop Quality and Sustainability)

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8 pages, 399 KiB

Open AccessReview

Breeding of Buckwheat to Reduce Bitterness and Rutin Hydrolysis

by Tatsuro Suzuki, Toshikazu Morishita, Takahiro Noda, Koji Ishiguro, Shiori Otsuka and Kenjiro Katsu

Plants 2021, 10(4), 791; https://doi.org/10.3390/plants10040791 - 16 Apr 2021

Cited by 24 | Viewed by 3517

Abstract

Buckwheat (Fagopyrum esculentum) is recognized as an important traditional crop in some regions, and its taste is an important characteristic. Of the three cultivated buckwheat species, Tartary buckwheat (Fagopyrum tataricum) and perennial buckwheat (Fagopyrum cymosum) have strong [...] Read more.

Buckwheat (Fagopyrum esculentum) is recognized as an important traditional crop in some regions, and its taste is an important characteristic. Of the three cultivated buckwheat species, Tartary buckwheat (Fagopyrum tataricum) and perennial buckwheat (Fagopyrum cymosum) have strong bitterness in their seeds, which has prevented the wider use of the seeds of these varieties. In Tartary buckwheat, some studies have focused on the cause of strong bitterness generation. Tartary buckwheat seeds contain large amounts of the functional compounds rutin and rutinosidase, and rutin hydrolysis by rutinosidase has been found to be the trigger of rutin hydrolysis. Therefore, a variety with only a trace of rutinosidase and with reduced bitterness is required. The rutinosidase in Tartary buckwheat seeds consists of two major isozymes with very similar enzymatic characteristics, which can hydrolyze flour rutin within several minutes after the addition of water. Recently, the trace-rutinosidase variety Manten-Kirari in Tartary buckwheat was developed. The trace-rutinosidase characteristics were dominated by a single recessive gene. In ‘Manten-Kirari’ dough and foods, such as breads, confectionaries, and noodles, the rutin residual ratio was higher and bitterness was reduced compared to that of the normal-rutinosidase variety. In this review, we summarize the detailed research on the breeding of buckwheat related to reducing bitterness and rutin hydrolysis. Full article

(This article belongs to the Special Issue Breeding Buckwheat for Nutritional Quality)

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Plants, Volume 10, Issue 4 (April 2021) – 210 articles

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