Editor’s Choice Articles

Selenium is an essential trace element which plays an important role in human immune regulation and disease prevention. Plants absorb inorganic selenium (selenite or selenate) from the soil and convert it into various organic selenides (such as seleno amino acids, selenoproteins, and volatile selenides) via the sulfur metabolic pathway. These organic selenides are important sources of dietary selenium supplementation for humans. Organoselenides can promote plant growth, improve nutritional quality, and play an important regulatory function in plant ecosystems. The release of selenium-containing compounds into the soil by Se hyperaccumulators can promote the growth of Se accumulators but inhibit the growth and distribution of non-Se accumulators. Volatile selenides with specific odors have a deterrent effect on herbivores, reducing their feeding on plants. Soil microorganisms can effectively promote the uptake and transformation of selenium in plants, and organic selenides in plants can improve the tolerance of plants to pathogenic bacteria. Although selenium is not an essential trace element for plants, the right amount of selenium has important physiological and ecological benefits for them. This review summarizes recent research related to the functions of selenium in plant ecosystems to provide a deeper understanding of the significance of this element in plant physiology and ecosystems and to serve as a theoretical basis and technical support for the full exploitation and rational application of the ecological functions of selenium-accumulating plants. Full article

The overexploitation of wild plants for medicinal uses and conventional agricultural farming methods, which use high amounts of water, fertilizers, and pesticides, have had devastating environmental consequences. This study aimed to evaluate the prospects of using aquaponics and hydroponics as alternative approaches to soil cultivation by comparing the crop yields, secondary metabolite contents, and the antifungal activities of ethanol extracts of Helichrysum odoratissimum (L.) Sweet, a widely used medicinal plant species in Southern Africa. Six-week-old H. odoratissimum seedlings were grown in aquaponic and hydroponic systems. The growth parameters, secondary metabolite contents, and antifungal activity against Fusarium oxysporum were assessed. The results for crop yield (plant height, fresh and dry weights) and the tissue nutrient contents did not change substantially (p > 0.05) between aquaponic and hydroponic treatments. Gas chromatography–mass spectrometry (GC–MS) analysis showed that monoterpenes and sesquiterpenes were the most abundant compounds in H. odoratissimum; however, no statistical difference was observed among the field, hydroponic, and aquaponic plants (DF = 2; χ² = 2.67; p > 0.05). While there was no significant difference in polyphenol contents among the three treatments, remarkably, the flavonol contents in the leaves varied significantly (DF = 2; χ² = 6.23; p < 0.05) among the three treatments. A higher flavonol content occurred in leaves from the hydroponic system than in leaves from the aquaponic (p < 0.05) and field (p > 0.05) systems. The MIC results showed that the ethanolic extract of H. odoratissimum was fungistatic against F. oxysporum; however, this effect was more prominent in the ethanol extracts of plants grown in the aquaponic system, with a mean MIC value of 0.37 ± 0.00 mg/mL The key findings of this study are that aquaponically cultivated plants exhibited the best antifungal activity, while higher total flavonol contents occurred in the hydroponically cultivated plants. In conclusion, aquaponics and hydroponics performed better or similar to field cultivation and are viable alternative methods for cultivating H. odoratissimum plants. Full article

The application of polyploidy in sustainable agriculture has already brought much appreciation among researchers. Polyploidy may occur naturally or can be induced in the laboratory using chemical or gaseous agents and results in complete chromosome nondisjunction. This comprehensive review described the potential of polyploidization on plants, especially its role in crop improvement for enhanced production and host-plant resistance development against pests and diseases. An in-depth investigation on techniques used in the induction of polyploidy, cytogenetic evaluation methods of different ploidy levels, application, and current research trends is also presented. Ongoing research has mainly aimed to bring the recurrence in polyploidy, which is usually detected by flow cytometry, chromosome counting, and cytogenetic techniques such as fluorescent in situ hybridization (FISH) and genomic in situ hybridization (GISH). Polyploidy can bring about positive consequences in the growth and yield attributes of crops, making them more tolerant to abiotic and biotic stresses. However, the unexpected change in chromosome set and lack of knowledge on the mechanism of stress alleviation is hindering the application of polyploidy on a large scale. Moreover, a lack of cost–benefit analysis and knowledge gaps on the socio-economic implication are predominant. Further research on polyploidy coupling with modern genomic technologies will help to bring real-world market prospects in the era of changing climate. This review on polyploidy provides a solid foundation to do next-generation research on crop improvement. Full article

In plant–insect interactions, calcium (Ca²⁺) variations are among the earliest events associated with the plant perception of biotic stress. Upon herbivory, Ca²⁺ waves travel long distances to transmit and convert the local signal to a systemic defense program. Reactive oxygen species (ROS), Ca²⁺ and electrical signaling are interlinked to form a network supporting rapid signal transmission, whereas the Ca²⁺ message is decoded and relayed by Ca²⁺-binding proteins (including calmodulin, Ca²⁺-dependent protein kinases, annexins and calcineurin B-like proteins). Monitoring the generation of Ca²⁺ signals at the whole plant or cell level and their long-distance propagation during biotic interactions requires innovative imaging techniques based on sensitive sensors and using genetically encoded indicators. This review summarizes the recent advances in Ca²⁺ signaling upon herbivory and reviews the most recent Ca²⁺ imaging techniques and methods. Full article

The cork layer present in all dicotyledonous plant species with radial growth is the result of the phellogen activity, a secondary meristem that produces phellem (cork) to the outside and phelloderm inwards. These three different tissues form the periderm, an efficient protective tissue working as a barrier against external factors such as environmental aggressions and pathogen attacks. The protective function offered by cork cells is mainly due to the abundance of suberin in their cell walls. Chemically, suberin is a complex aliphatic network of long chain fatty acids and alcohols with glycerol together with aromatic units. In most woody species growing in temperate climates, the first periderm is replaced by a new functional periderm upon a few years after being formed. One exception to this bark development can be found in cork oak (Quercus suber) which display a single periderm that grows continuously. Quercus suber stands by its thick cork layer development with continuous seasonal growth. Cork raw material has been exploited by man for centuries, especially in Portugal and Spain. Nowadays, its applications have widened vastly, from the most known product, stoppers, to purses or insulating materials used in so many industries, such as construction and car production. Research on how cork develops, and the effect environmental factors on cork oak trees is extremely important to maintain production of good-quality cork, and, by maintaining cork oak stands wealthy, we are preserving a very important ecosystem both by its biodiversity and its vital social and economic role in areas already showing a population declination. Full article

Sustainable agricultural systems based on the application of phyto-friendly bacteria and fungi are increasingly needed to preserve soil fertility and microbial biodiversity, as well as to reduce the use of chemical fertilizers and pesticides. Although there is considerable attention on the potential applications of microbial consortia as biofertilizers and biocontrol agents for crop management, knowledge on the molecular responses modulated in host plants because of these beneficial associations is still incomplete. This review provides an up-to-date overview of the different mechanisms of action triggered by plant-growth-promoting microorganisms (PGPMs) to promote host-plant growth and improve its defense system. In addition, we combined available gene-expression profiling data from tomato roots sampled in the early stages of interaction with Pseudomonas or Trichoderma strains to develop an integrated model that describes the common processes activated by both PGPMs and highlights the host’s different responses to the two microorganisms. All the information gathered will help define new strategies for the selection of crop varieties with a better ability to benefit from the elicitation of microbial inoculants. Full article

Plants produce a wide variety of bioactive compounds with insecticidal properties, such as secondary metabolites capable of interfering with the nutrition and reproduction of pest species such as Plutella xylostella. Thus, the objective of this study was to evaluate the effects of aqueous and ethanolic extracts of Ludwigia spp. (Onagraceae) on the feeding and oviposition of P. xylostella. Choice bioassays were performed using aqueous and ethanolic extracts. The aqueous extract of L. tomentosa resulted in an approximately 81% reduction in larval feeding compared to that in the control, with an antifeedant index (AI) of 52%. The aqueous and ethanolic extract of L. nervosa acted by stimulating larval feeding. The oviposition was significantly reduced in the kale leaves treated with aqueous and ethanolic extracts of Ludwigia spp. The aqueous extracts promoted an average 90% reduction in oviposition when compared to that in the control, and an oviposition deterrent index (ODI) above 61% was classified as an oviposition deterrent. In addition, ethanolic extracts affected 81% of oviposition, with an ODI above 41%. Bioassays should be performed to clarify the use of aqueous and ethanolic extracts of L. nervosa as they acted as phagostimulants in the feeding tests and as deterrents in the oviposition tests. The phenolic compounds—flavonoids, condensed tannins, and alkaloids—were more abundant in L. nervosa, L. tomentosa, L. sericea, and L. longifolia. The extracts of L. longifolia and L. tomentosa showed the best results, interfering with the host choice for feeding and oviposition in P. xylostella and representing an alternative for the control of diamondback moths. Full article

Gibberellins have been classically related to a few key developmental processes, thus being essential for the accurate unfolding of plant genetic programs. After more than a century of research, over one hundred different gibberellins have been described. There is a continuously increasing interest in gibberellins research because of their relevant role in the so-called "Green Revolution", as well as their current and possible applications in crop improvement. The functions attributed to gibberellins have been traditionally restricted to the regulation of plant stature, seed germination, and flowering. Nonetheless, research in the last years has shown that these functions extend to many other relevant processes. In this review, the current knowledge on gibberellins homeostasis and mode of action is briefly outlined, while specific attention is focused on the many different responses in which gibberellins take part. Thus, those genes and proteins identified as being involved in the regulation of gibberellin responses in model and non-model species are highlighted. The present review aims to provide a comprehensive picture of the state-of-the-art perception of gibberellins molecular biology and its effects on plant development. This picture might be helpful to enhance our current understanding of gibberellins biology and provide the know-how for the development of more accurate research and breeding programs. Full article

The distribution of global warming has been varying both diurnally and seasonally. Little is known about the spatiotemporal variations in the relationships between vegetation greenness and day- and night-time warming during the last decades. We investigated the global inter- and intra-annual responses of vegetation greenness to the diurnal asymmetric warming during the period of 1982–2015, using the normalized different vegetation index (NDVI, a robust proxy for vegetation greenness) obtained from the NOAA/AVHRR NDVI GIMMS3g dataset and the monthly average daily maximum (T_max) and minimum temperature (T_min) obtained from the gridded Climate Research Unit, University of East Anglia. Several findings were obtained: (1) The strength of the relationship between vegetation greenness and the diurnal temperature varied on inter-annual and seasonal timescales, indicating generally weakening warming effects on the vegetation activity across the global. (2) The decline in vegetation response to T_max occurred mainly in the mid-latitudes of the world and in the high latitudes of the northern hemisphere, whereas the decline in the vegetation response to T_min primarily concentrated in low latitudes. The percentage of areas with a significantly negative trend in the partial correlation coefficient between vegetation greenness and diurnal temperature was greater than that of the areas showing the significant positive trend. (3) The trends in the correlation between vegetation greenness and diurnal warming showed a complex spatial pattern: the majority of the study areas had undergone a significant declining strength in the vegetation greenness response to T_max in all seasons and to T_min in seasons except autumn. These findings are expected to have important implications for studying the diurnal asymmetry warming and its effect on the terrestrial ecosystem. Full article

Anacardium occidentale L. is used throughout the world to treat type 2 diabetes. In Portugal, a traditional herbal preparation made with stem bark of this species (AoBTHP) has been used for more than 30 years to treat this pathology. The AoBTHP was standardized on total phenolic content, and its hypoglycemic activity was assessed using db/db mice (n = 26) for 92 days. Three doses (40.2, 71.5, and 127.0 mg/kg/day, per os) were tested, and glibenclamide (5 mg/kg/day) was used as positive control. During the study, glycemia was measured under non-fasting or fasting states. In sequence, thin-layer chromatography bioautographic assays were used for the detection of possible alpha- and beta-glucosidase inhibitors. A significant hypoglycemic effect in fasting glycemia in days 31 and 57 was observed with the three tested doses. The 71.5 mg/kg and 127.0 mg/kg AoBTHPs significantly reduced non-fasting glycemia on day 24. The highest dose showed the most significant hypoglycemic effect. Gallic acid was identified as the major alpha- and beta-glucosidase inhibitor. The 127 mg/kg/day AoBTHP dose showed a greater glucose-lowering effect than glibenclamide. For the first time, a standardized AoBTHP was tested using an in vivo diabetes model, and its usage was preclinically validated for type 2 diabetes treatment. The hypoglycemic activity of an AoBTHP can be related to the presence of alpha- and beta-glucosidase inhibitors, such as gallic acid, but other mechanisms can also be involved. Full article

Leaf extract of Cydonia Oblonga Mill. is interesting for further exploration of the potential of its substrates for therapeutic supplements. Quantitative and qualitative analyses were conducted on samples of green (October), yellow (November), and brown (December) quince leaves collected in the region of Pinhel, Portugal. Mineral analysis determined the measurements of the levels of several macro- and micro-elements. Organic analysis assessed the moisture content, total phenolic content (TPC), vitamin E, and fatty acid (FA) profiles. Mineral analysis was based on ICP-MS techniques, while the profiles of vitamin E and FA relied on HPLC-DAD-FLD and GC-FID techniques, respectively. Moisture content was determined through infrared hygrometry and TPC was determined by spectrophotometric methods. Regarding the mineral content, calcium, magnesium, and iron were the most abundant minerals. Concerning organic analysis, all leaf samples showed similar moisture content, while the TPC of gallic acid equivalents (GAE) and total vitamin E content, the most predominant of which was the α-tocopherol isomer, showed significant variations between green-brown and yellow leaves. FA composition in all leaf samples exhibited higher contents of SFA and PUFA than MUFA, with a predominance of palmitic and linolenic acids. Organic and inorganic analysis of quince leaves allow for the prediction of adequate physiological properties, mainly cardiovascular, pulmonary, and immunological defenses, which with our preliminary in silico studies suggest an excellent supplement to complementary therapy, including drastic pandemic situations. Full article

Protein-protein interaction studies provide valuable insights into cellular signaling. Brassinosteroid (BR) signaling is initiated by the hormone-binding receptor Brassinosteroid Insensitive 1 (BRI1) and its co-receptor BRI1 Associated Kinase 1 (BAK1). BRI1 and BAK1 were shown to interact independently with the Receptor-Like Protein 44 (RLP44), which is implicated in BRI1/BAK1-dependent cell wall integrity perception. To demonstrate the proposed complex formation of BRI1, BAK1 and RLP44, we established three-fluorophore intensity-based spectral Förster resonance energy transfer (FRET) and FRET-fluorescence lifetime imaging microscopy (FLIM) for living plant cells. Our evidence indicates that RLP44, BRI1 and BAK1 form a ternary complex in a distinct plasma membrane nanodomain. In contrast, although the immune receptor Flagellin Sensing 2 (FLS2) also forms a heteromer with BAK1, the FLS2/BAK1 complexes are localized to other nanodomains. In conclusion, both three-fluorophore FRET approaches provide a feasible basis for studying the in vivo interaction and sub-compartmentalization of proteins in great detail. Full article

Helichrysum species are prominent South African medicinal plants. From the essential oils (EOs) of three Helichrysum species, H. petiolare, H. odoratissimum, and H. cymosum, sixty-three constituent components were identified, with hydrocarbons and oxygenated monoterpenes and sesquiterpenes as major components. The compounds were analyzed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy. In H. petiolare EO, the major components were faurinone (20.66%) and (E)-β-ocimene (17.21%). Faurinone was isolated from this EO for the first time. In H. odoratissimum, 1,8-cineole (17.44%) and α-pinene, and γ-curcumene (15.76%) were the major components whereas, in H. cymosum, α-pinene (29.82%) and (E)-caryophyllene (19.20%) were the major components. In the antibacterial activity study, the EOs were tested against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The EOs were found to possess low antibacterial, anti-tyrosinase, and photoprotection activities and moderate antioxidant capacities, thus establishing these Helichrysum EOs as valuable antioxidant agents. Full article

Improvement of the storage quality of rice is a critical challenge for the scientific community. This study assesses the effects of the irrigation with hydrogen nanobubble water (HNW) on the storage quality of rice (Oryza sativa ‘Huruan1212’). Compared with ditch water control, after one year of storage at 25 °C and 70% RH, the HNW-irrigated rice had higher contents of essential amino acids, especially lysine. Importantly, the generation of off-flavors in the stored rice was significantly decreased, which was confirmed by the lower levels of volatile substances, including pentanal, hexanal, heptanal, octanal, 1-octen-3-ol, and 2-heptanone. The subsequent results showed that the HNW-irrigated rice not only retained lower levels of free fatty acid values, but also had increased antioxidant capacity and decreased lipoxygenase activity and transcripts, thus resulting in decreased lipid peroxidation. This study opens a new window for the practical application of HNW irrigation in the production and subsequent storage of crops. Full article

The aim of the present study was to compare tolerance to salinity and ion accumulation potential of Armeria maritima subsp. elongata. Three accessions (AM1 and AM2, both from Latvia, and AM3 from Sweden) from relatively dry sandy soil habitats in the Baltic Sea region were selected and compared using both in vitro cultivated shoot explants and long-term soil-cultivated plants at flowering stage. Growth of root non-forming explants treated with increasing concentrations of NaCl was significantly inhibited starting from 110 mmol L⁻¹, and the rate of shoot formation was even more sensitive. Significant differences in morphology and responses to salinity were found between different accessions. For soil-grown plants, biomass accumulation in above-ground parts was relatively little affected by salinity in AM1 and AM2 in comparison to that in AM3. Differences in ion accumulation were evident between the accessions as well as in respect to cultivation system used. Maximum accumulation capacity for Na⁺ was up to 2.5 mol kg⁻¹ both in shoot explant tissues and in old leaves of soil-grown plants treated with NaCl, but that for K⁺ reached 4.0 mol kg⁻¹ in old leaves of soil-grown plants treated with KCl. Non-ionic component of osmotic value was relatively high in old leaves and significantly increased under NaCl treatment, especially for AM2 and AM3 plants at moderate salinity, but in AM1 only at high salinity. In contrast, it significantly decreased in old leaves of AM2 plants treated with increasing concentration of KCl. It can be concluded that a wide salinity tolerance exists within A. maritima accessions from dry sandy soil habitats, associated with the ability to accumulate surplus ions both in salt glands and old leaves. Full article

The sessile plant has developed mechanisms to survive the “rough and tumble” of its natural surroundings, aided by its evolved innate immune system. Precise perception and rapid response to stress stimuli confer a fitness edge to the plant against its competitors, guaranteeing greater chances of survival and productivity. Plants can “eavesdrop” on volatile chemical cues from their stressed neighbours and have adapted to use these airborne signals to prepare for impending danger without having to experience the actual stress themselves. The role of volatile organic compounds (VOCs) in plant–plant communication has gained significant attention over the past decade, particularly with regard to the potential of VOCs to prime non-stressed plants for more robust defence responses to future stress challenges. The ecological relevance of such interactions under various environmental stresses has been much debated, and there is a nascent understanding of the mechanisms involved. This review discusses the significance of VOC-mediated inter-plant interactions under both biotic and abiotic stresses and highlights the potential to manipulate outcomes in agricultural systems for sustainable crop protection via enhanced defence. The need to integrate physiological, biochemical, and molecular approaches in understanding the underlying mechanisms and signalling pathways involved in volatile signalling is emphasised. Full article

Environmental changes are inevitable with time, but their intensification and diversification, occurring in the last several decades due to the combination of both natural and human-made causes, are really a matter of great apprehension. As a consequence, plants are exposed to a variety of abiotic stressors that contribute to their morpho-physiological, biochemical, and molecular alterations, which affects plant growth and development as well as the quality and productivity of crops. Thus, novel strategies are still being developed to meet the challenges of the modern world related to climate changes and natural ecosystem degradation. Innovative methods that have recently received special attention include eco-friendly, easily available, inexpensive, and, very often, plant-based methods. However, such approaches require better cognition and understanding of plant adaptations and acclimation mechanisms in response to adverse conditions. In this succinct review, we have highlighted defense mechanisms against external stimuli (mainly exposure to elevated levels of metal elements) which can be activated through permanent microevolutionary changes in metal-tolerant species or through exogenously applied priming agents that may ensure plant acclimation and thereby elevated stress resistance. Full article

Imperata cylindrica is native to Southeast Asia and East Africa and has become naturalized in humid tropics, subtropics and warmer temperate zones of the world. The species is one of the top ten worst weeds in the worlds and is listed among the world’s top 100 worst invasive alien species. It is an aggressive colonizer and forms large monospecific stands in several countries. Possible evidence of the allelopathy of I. cylindrica has been accumulated in the literature over three decades. The extracts, leachates, root exudates, decomposing residues and rhizosphere soil of I. cylindrica were found to suppress the germination and growth of several plant species, including woody plant species, and to reduce their rhizobium nodulation and mycorrhizal colonization. Several allelochemicals, such as fatty acids, terpenoids, simple phenolics, benzoic acids, phenolic acids, phenolic aldehydes, phenylpropanoids, flavonoids, quinones and alkaloids, were also found in the extracts, leachates, root exudates and/or growth medium of I. cylindrica. These observations suggest that allelochemicals may be synthesized in I. cylindrica and released into the rhizosphere soil and surrounding environments either by the leachates, root exudation or decomposition process of plant parts, and certain allelochemicals may contribute to the alteration of the microbial community, including rhizobia and mycorrhizal fungi, suppressing the regeneration process of native plant species through the inhibition of their germination and growth. Therefore, the allelopathy of I. cylindrica may support its invasiveness, naturalization and formation of large monospecific stands. This is the first review article focusing on the allelopathy of I. cylindrica. Full article

Plant growth regulators (PGRs) are natural hormones and synthetic hormone analogues. At low concentrations, PGRs have the ability to influence cell division, cell expansion, and cell structure and function, in addition to mediating environmental stress. In this study, experiments were conducted to determine how exogenous PGRs indole acetic acid (IAA), abscisic acid (ABA), and gibberellic acid (GA) influenced osmotic regulatory substances and activity of antioxidant enzymes in Nitraria tangutorum. Using a completely randomized design, IAA, ABA, and GA3 were applied as foliar spray at concentrations of 50 mg/L, 100 mg/L, 150 mg/L, and 200 mg/L to N. tangutorum shrubs. Some selected shrubs did not receive any treatment and served as the control (Ck). The results showed that the foliar spray of IAA, ABA, and GA3 significantly increased the content of osmotic regulatory substances (soluble sugar, soluble protein, and proline) and antioxidant enzymes (SOD and POD) at most concentrations. In addition, the malondialdehyde (MDA) content significantly reduced after treatment, but after regrowth of coppiced shrubs, lipid peroxidation increased and was still lower than Ck. Our study provides evidence that 100 mg/L 150 mg/L, and 200 mg/L concentrations of IAA, ABA, and GA3 treatments are effective for enhancing osmotic regulatory substances and the activity of antioxidant enzymes in N. tangutorum, which offers an effective strategy not only for increasing tolerance to abiotic and biotic stresses, but also improving the adaptability of N. tangutorum shrubs to the environment. Full article

The ubiquitin–proteasome system (UPS) is crucial in maintaining cellular physiological balance. The UPS performs quality control and degrades proteins that have already fulfilled their regulatory purpose. The UPS is essential for cellular and organic homeostasis, and its functions regulate DNA repair, gene transcription, protein activation, and receptor trafficking. Besides that, the UPS protects cellular immunity and acts on the host’s defense system. In order to produce successful infections, viruses frequently need to manipulate the UPS to maintain the proper level of viral proteins and hijack defense mechanisms. This review highlights and updates the mechanisms and strategies used by plant viruses to subvert the defenses of their hosts. Proteins involved in these mechanisms are important clues for biotechnological approaches in viral resistance. Full article

Plants are key components of the terrestrial ecosystem carbon cycle. Atmospheric CO₂ is assimilated through photosynthesis and stored in plant biomass and in the soil. The use of turfgrass is expanding due to the increasing human population and urbanization. In this review, we summarize recent carbon sequestration research in turfgrass and compare turfgrass systems to other plant systems. The soil organic carbon (SOC) stored in turfgrass systems is comparable to that in other natural and agricultural systems. Turfgrass systems are generally carbon-neutral or carbon sinks, with the exception of intensively managed areas, such as golf course greens and athletic fields. Turfgrass used in other areas, such as golf course fairways and roughs, parks, and home lawns, has the potential to contribute to carbon sequestration if proper management practices are implemented. High management inputs can increase the biomass productivity of turfgrass but do not guarantee higher SOC compared to low management inputs. Additionally, choosing the appropriate turfgrass species that are well adapted to the local climate and tolerant to stresses can maximize CO₂ assimilation and biomass productivity, although other factors, such as soil respiration, can considerably affect SOC. Future research is needed to document the complete carbon footprint, as well as to identify best management practices and appropriate turfgrass species to enhance carbon sequestration in turfgrass systems. Full article

The rhizosphere is a thin film of soil that surrounds plant roots and the primary location of nutrient uptake, and is where important physiological, chemical, and biological activities are occurring. Many microbes invade the rhizosphere and have the capacity to promote plant growth and health. Bacillus spp. is the most prominent plant growth promoting rhizobacteria due to its ability to form long-lived, stress-tolerant spores. Bacillus-plant interactions are driven by chemical languages constructed by a wide spectrum of metabolites and lead to enhanced plant growth and defenses. Thus, this review is a synthesis and a critical assessment of the current literature on the application of Bacillus spp. in agriculture, highlighting gaps that remain to be explored to improve and expand on the Bacillus-based biostimulants. Furthermore, we suggest that omics sciences, with a focus on metabolomics, offer unique opportunities to illuminate the chemical intercommunications between Bacillus and plants, to elucidate biochemical and molecular details on modes of action of Bacillus-based formulations, to generate more actionable insights on cellular and molecular events that explain the Bacillus-induced growth promotion and stress resilience in plants. Full article

Consumer awareness and demands for quality eco-friendly food products have made scientists determined to concentrate their attention on sustainable advancements in the utilization of bioactive compounds for increasing safety and food quality. Essential oils (EOs) are extracted from plants and exhibit antimicrobial (antibacterial and antifungal) activity; thus, they are used in food products to prolong the shelf-life of foods by limiting the growth or survival of microorganisms. In vitro studies have shown that EOs are effective against foodborne bacteria, such as Escherichia coli, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus. The growing interest in essential oils and their constituents as alternatives to synthetic preservatives has been extensively exploited in recent years, along with techniques to facilitate the implementation of their application in the food industry. This paper’s aim is to evaluate the current knowledge on the applicability of EOs in food preservation, and how this method generally affects technological properties and consumers’ perceptions. Moreover, essential aspects concerning the limitation of the available alternatives are highlighted, followed by a presentation of the most promising trends to streamline the EOs’ usability. Incorporating EOs in packaging materials is the next step for green and sustainable foodstuff production and a biodegradable method for food preservation. Full article

Drought stress constrains plant cell metabolism and induces the production of reactive oxygen species (ROS). In response to drought stress, plants induce a series of physiological and biochemical changes, scavenging ROS. Among soil microbes, arbuscular mycorrhizal fungi (AMF) are found to be effective ameliorators of ROS under drought-stress conditions. However, the comprehensive roles of the oxidative stress ameliorators mediated by AMF in alleviating drought stress are not studied in detail. The present study aims to determine the oxidative stress ameliorators using meta-analysis highlighting AMF inoculation efficacy on drought stress alleviation. The results confirmed that AMF inoculation had a significant reduction in hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and electrolyte leakage (EL). Nevertheless, proline accumulation was found to have a non-significant correlation with AMF inoculation. Further, carotenoids and soluble sugars increased positively in AMF-inoculated plants under drought stress and there was a subsequent reduction of abscisic acid (ABA). The results of the meta-analysis reveal the benefits of AMF inoculation with reduced H₂O₂ levels leading to reduced lipid peroxidation (MDA) and increased membrane stability (EL). Thus, the present assessment reveals the sequence of events involved in eliciting drought stress alleviation due to AMF inoculation. Full article

Drought affects common bean productivity, and the severity of its impact is expected to increase due to climate change. The use of versatile genotypes could contribute to securing future bean production. This study investigates the adaptability of 10 common bean genotypes of indeterminate growth type under water scarcity conditions by measuring agronomic and physiological parameters. The evaluation occurs under irrigation treatments applied at two different phenological stages (anthesis (WDA) and seed filling initiation (WDSF)). The recorded adaptabilities of the genotypes (G) showed that G10 produced the highest overall seed yield in the normal irrigation (NI) (197.22 g plant⁻¹) and WDA (192.78 g plant⁻¹), while the G6 had the highest yield at WDSF (196.71 g plant⁻¹). For the genotype’s average mean, chlorophyll content decreased by 10.5% under drought at WDSF. Net photosynthetic rate (P_n), stomatal conductance (g_s), and transpiration rate (E) were reduced at WDA by 53%, 80.8%, and 61.4% and at WDSF by 43.75%, 57.7%, and 36%, respectively, while relative water content (RWC) reduced by 16.48%, on average, for both stages. G10 and G6 showed adaptability when water scarcity occurred at an early (WDA) or later stage (WDSF), respectively, providing insights into using germplasm resources to cope with the drought effect. Full article

Drought generates a complex scenario worldwide in which agriculture should urgently be reframed from an integrative point of view. It includes the search for new water resources and the use of tolerant crops and genotypes, improved irrigation systems, and other less explored alternatives that are very important, such as biotechnological tools that may increase the water use efficiency. Currently, a large body of evidence highlights the role of specific strains in the main microbial rhizosphere groups (arbuscular mycorrhizal fungi, yeasts, and bacteria) on increasing the drought tolerance of their host plants through diverse plant growth-promoting (PGP) characteristics. With this background, it is possible to suggest that the joint use of distinct PGP microbes could produce positive interactions or additive beneficial effects on their host plants if their co-inoculation does not generate antagonistic responses. To date, such effects have only been partially analyzed by using single omics tools, such as genomics, metabolomics, or proteomics. However, there is a gap of information in the use of multi-omics approaches to detect interactions between PGP and host plants. This approach must be the next scale-jump in the study of the interaction of soil–plant–microorganism. In this review, we analyzed the constraints posed by drought in the framework of an increasing global demand for plant production, integrating the important role played by the rhizosphere biota as a PGP agent. Using multi-omics approaches to understand in depth the processes that occur in plants in the presence of microorganisms can allow us to modulate their combined use and drive it to increase crop yields, improving production processes to attend the growing global demand for food. Full article

One of the most important proxy archives for past climate variation is tree rings. Tree-ring parameters offer valuable knowledge regarding how trees respond and adapt to environmental changes. Trees encode all environmental changes in different tree-ring parameters. In this study, we analyzed how air temperature is encoded in different Norway spruce tree-ring proxies along an altitude gradient in an intramountain valley of the Carpathians. The study area, in the Gheorgheni region, Romania (Eastern Carpathians), has a mountain climate with a frequent temperature inversion in winter. The climate–growth relationship was analyzed for two contrasting altitudes: low elevation, i.e., below 1000 m a.s.l., and high elevation, i.e., above 1500 m a.s.l. Two local weather stations, one in the valley and the other on the upper part of the mountains, provide daily temperatures (Joseni—750 m a.s.l. and Bucin—1282 m a.s.l.). The bootstrap Pearson correlation between cumulative daily temperature data and three tree-ring proxies (tree-ring width—TRW, basal area increment—BAI, and blue intensity—BI) was computed for each series. The results show that elevation modulates the climate response pattern in the case of BI, and remains relatively similar for TRW and BAI. The winter temperature’s positive influence on spruce growth was observed in both TRW and BAI chronologies. Additionally, the BAI chronology highlights a positive relationship with summer temperature. The highest correlation coefficient (r = 0.551, p < 0.05, n = 41) was recorded between BI residual chronology from high elevation series and summer/autumn temperature from the upper-part weather station for a cumulative period of 59 days (the second half of August to the beginning of October). Our results show that, for this intramountain valley of the Eastern Carpathians, different tree-ring proxies capture different climate signals. Full article

Clary sage (Salvia sclarea L.) is a medicinal plant that has the potential to be used for phytoextraction of zinc (Zn) and cadmium (Cd) from contaminated soils by accumulating these metals in its tissues. Additionally, it has been found to be more tolerant to excess Zn than to Cd stress alone; however, the interactive effects of the combined treatment with Zn and Cd on this medicinal herb, and the protective strategies of Zn to alleviate Cd toxicity have not yet been established in detail. In this study, clary sage plants grown hydroponically were simultaneously exposed to Zn (900 µM) and Cd (100 μM) for 8 days to obtain more detailed information about the plant responses and the role of excess Zn in mitigating Cd toxicity symptoms. The leaf anatomy, photosynthetic pigments, total phenolic and anthocyanin contents, antioxidant capacity (by DPPH and FRAP analyses), and the uptake and distribution of essential elements were investigated. The results showed that co-exposure to Zn and Cd leads to an increased leaf content of Fe and Mg compared to the control, and to increased leaf Ca, Mn, and Cu contents compared to plants treated with Cd only. This is most likely involved in the defense mechanisms of excess Zn against Cd toxicity to protect the chlorophyll content and the functions of both photosystems and the oxygen-evolving complex. The data also revealed that the leaves of clary sage plants subjected to the combined treatment have an increased antioxidant capacity attributed to the higher content of polyphenolic compounds. Furthermore, light microscopy indicated more alterations in the leaf morphology after Cd-only treatment than after the combined treatment. The present study shows that excess Zn could mitigate Cd toxicity in clary sage plants. Full article

Since medicinal plants are widely used in treating various diseases, phytoconstituents enrichment strategies are of high interest for plant growers. First of all, we investigated the impact of phytosociological cultivation on polyphenolic content (total flavonoids—TFL, and total polyphenols—TPC) of peppermint (Mentha piperita L.) and lemon balm (Melissa officinalis L.) leaves, using spectrophotometric methods. Secondly, the influence of chemical (NPK) and organic (BIO) fertilization on polyphenolic content and plant material quality was also assessed. Dry extracts were obtained from harvested leaves using hydroethanolic extraction solvents for further qualitative and quantitative assessment of phytoconstituents by FT-ICR MS and UHPLC-MS. Furthermore, the antioxidant activity of leaf extracts was determined in vitro using DPPH, ABTS and FRAP methods. Molecular docking simulations were employed to further evaluate the antioxidant potential of obtained extracts, predicting the interactions of identified phytochemicals with sirtuins. The concentration of polyphenols was higher in the plant material harvested from the phytosociological culture. Moreover, the use of BIO fertilizer led to the biosynthesis of a higher content of polyphenols. Higher amounts of phytochemicals, such as caffeic acid, were determined in extracts obtained from phytosociological crops. The antioxidant activity was dependent on polyphenols concentration, more potent inhibition values being observed for the extracts obtained from the phytosociological batches. Molecular docking studies and MM/PBSA calculations revealed that the obtained extracts have the potential to directly activate sirtuins 1, 5 and 6 through several polyphenolic compounds, such as rosmarinic acid, thus complementing the free radical scavenging activity with the potential stimulation of endogenous antioxidant defense mechanisms. In conclusion, growing medicinal plants in phytosociological cultures treated with biofertilizers can have a positive impact on plant material quality, concentration in active constituents and biological activity. Full article

Sapindus mukorossi Gaertn., also called the washnut, is a tropical tree of the Sapindaceae family. The plant owes its name to its cleaning and washing properties used by the local population as a natural detergent. The most important ingredients of the plant are triterpenoid saponins contained in many parts of the plant, inducing fruits, galls, or roots. The tree also contains other valuable, biologically active compounds that are obtained by extraction methods. Raw or purified extract and isolated saponins are valuable plant products that can be used in the food, pharmaceutical, cosmetic, and chemical industries. This review includes the most important biological and surfactant properties of extracts and isolated saponins obtained from various parts of the plant. Full article

The northern red oak (Quercus rubra L.) is an ornamental oak species native to eastern America, being an invasive species in Europe, with increasing coverage. The aim of this work was to evaluate the biological potential of red oak bark extracts. Aqueous and ethanolic preparations were obtained by two extraction methods: ultrasonic-assisted extraction (UAE) and microwave assisted extraction (MAE). The total phenolic and tannin contents were measured using spectrophotometric methods. The antioxidant activity was evaluated by two complementary methods (DPPH and ABTS). Antimicrobial potential was tested against five bacteria and three Candida species, and the effect on biofilm formation and synergism with gentamicin was also evaluated. Finally, enzyme inhibitory properties were assessed for α-glucosidase, tyrosinase, and acetylcholinesterase. The results indicated a higher phenolic content for the extracts obtained through MAE, while UAE bark extracts were rich in tannins. All the extracts exhibited antioxidant, anti-glucosidase, and anti-tyrosinase activity, while the antibacterial potential was mostly observed for the MAE extracts, especially against S. aureus, C. parapsilopsis, and C. krusei; inhibition of biofilm formation was observed only for MRSA. These findings show that the red oak bark might be an important source of bioactive compounds with antioxidant and antimicrobial properties. Full article

Polyploid induction is of utmost importance in horticultural plants for the development of new varieties with desirable morphological and physiological traits. Polyploidy may occur naturally due to the formation of unreduced gametes or can be artificially induced by doubling the number of chromosomes in somatic cells. In this experiment, a protocol for in vitro polyploid induction of highbush blueberry (Vaccinium corymbosum L.) leaf tissues was studied by using different concentrations of colchicine and oryzalin. Oryzalin was found to be highly toxic to this species, while the adventitious shoot organogenesis media enriched with 25 and 250 µM colchicine was able to induce polyploidization, with significant differences among the treatments used. Higher concentrations of both antimitotic agents led to the browning and death of the leaf tissues. The polyploids obtained showed several morphological differences when compared with the diploid shoots. Flow cytometry analysis was used to confirm the ploidy level of the regenerated shoots, demonstrating that a total of 15 tetraploids and 34 mixoploids were obtained. The stomatal sizes (length and width) of the tetraploids were larger than those of the diploids, but a reduced stomatal density was observed as compared to the controls. These shoots will be acclimatized and grown until they reach the reproductive phase in order to test their potential appeal as new varieties or their use for breeding and genetic improvement. Full article

Extensive research has been performed on the in-field nondestructive evaluation (NDE) of the physicochemical properties of ‘Madoka’ peaches, such as chromaticity (a*), soluble solids content (SSC), firmness, and titratable acidity (TA) content. To accomplish this, a snapshot-based hyperspectral imaging (HSI) approach for filed application was conducted in the visible and near-infrared (Vis/NIR) region. The hyperspectral images of ‘Madoka’ samples were captured and combined with commercial HSI analysis software, and then the physicochemical properties of the ‘Madoka’ samples were predicted. To verify the performance of the field-based HSI application, a lab-based HSI application was also conducted, and their coefficient of determination values (R²) were compared. Finally, pixel-based chemical images were produced to interpret the dynamic changes of the physicochemical properties in ‘Madoka’ peach. Consequently, the a* values and SSC content shows statistically significant R² values (0.84). On the other hand, the firmness and TA content shows relatively lower accuracy (R² = 0.6 to 0.7). Then, the resultant chemical images of the a* values and SSC content were created and could represent their different levels using grey scale gradation. This indicates that the HSI system with integrated HSI software used in this work has promising potential as an in-field NDE for analyzing the physicochemical properties in ‘Madoka’ peaches. Full article

Lignans are a group of natural polyphenols present in medicinal plants and in plants which are a part of the human diet for which more and more pharmacological activities, such as antimicrobial, anti-inflammatory, hypoglycemic, and cytoprotective, are being reported. However, it is their cytotoxic activities that are best understood and which have shed light on this group. Two anticancer drugs, etoposide, and teniposide, were derived from a potent cytotoxic agent—podophyllotoxin from the roots of Podophyllum peltatum. The evidence from clinical and observational studies suggests that human microbiota metabolites (enterolactone, enterodiol) of dietary lignans (secoisolariciresinol, pinoresinol, lariciresinol, matairesinol, syringaresinol, medioresinol, and sesamin) are associated with a reduced risk of some hormone-dependent cancers. The biological in vitro, pharmacological in vivo investigations, and clinical studies demand significant amounts of pure compounds, as well as the use of well-defined and standardized extracts. That is why proper extract preparation, optimization of lignan extraction, and identification are crucial steps in the development of lignan use in medicine. This review focuses on lignan extraction, purification, fractionation, separation, and isolation methods, as well as on chromatographic, spectrometric, and spectroscopic techniques for their qualitative and quantitative analysis. Full article

Pea rust is a major disease worldwide caused by Uromyces pisi in temperate climates. Only moderate levels of partial resistance against U. pisi have been identified so far in pea, urging for enlarging the levels of resistance available for breeding. Herein, we describe the responses to U. pisi of 320 Pisum spp. accessions, including cultivated pea and wild relatives, both under field and controlled conditions. Large variations for U. pisi infection response for most traits were observed between pea accessions under both field and controlled conditions, allowing the detection of genotypes with partial resistance. Simultaneous multi-trait indexes were applied to the datasets allowing the identification of partial resistance, particularly in accessions JI224, BGE004710, JI198, JI199, CGN10205, and CGN10206. Macroscopic observations were complemented with histological observations on the nine most resistant accessions and compared with three intermediates and three susceptible ones. This study confirmed that the reduced infection of resistant accessions was associated with smaller rust colonies due to a reduction in the number of haustoria and hyphal tips per colony. Additionally, a late acting hypersensitive response was identified for the first time in a pea accession (PI273209). These findings demonstrate that screening pea collections continues to be a necessary method in the search for complete resistance against U. pisi. In addition, the large phenotypic diversity contained in the studied collection will be useful for further association analysis and breeding perspectives. Full article

Drought affects crop developmentnand growth. To explore the physiological effects of drought stress on soybean, HeiNong44 (HN44) and HeiNong65 (HN65) varieties were used as experimental materials and PEG-6000 was used as the osmotic medium. The antioxidant enzyme activity, osmotic adjustment substance content, antioxidant capacity, and endogenous hormone content of the two soybean varieties were studied under different drought degrees and different treatment durations. Drought stress caused significant physiological changes in soybean. The antioxidant enzyme activities, osmoregulation substance content, and total antioxidant capacity (T-AOC) of HN65 and HN44 showed an increasing trend under mild and moderate drought, however, they first increased and then decreased under severe drought conditions. Following the extension of treatment time, malondialdehyde (MDA) showed an increasing trend. As drought increased, gibberellin (GA) content showed a decreasing trend, while abscisic acid (ABA), salicylic acid (SA), and zeatin nucleoside (ZA) content showed an increasing trend. The auxin (IAA) content of the two varieties showed opposite change trends. In short, drought had a significant impact on the physiology of these two soybean varieties; however, overall, the drought resistance of HN65 was lower than that of HN44. This study provides a research theoretical basis for addressing the drought resistance mechanism and the breeding of drought resistant soybean varieties. Full article

Drought is one of the biggest concerns in agriculture due to the projected reduction of global freshwater supply with a concurrent increase in global food demand. Roots can significantly contribute to improving drought adaptation and productivity. Plants increase water uptake by adjusting root architecture and cooperating with symbiotic soil microbes. Thus, emphasis has been given to root architectural responses and root–microbe relationships in drought-resilient crop development. However, root responses to drought adaptation are continuous and complex processes and involve additional root traits and interactions among themselves. This review comprehensively compiles and discusses several of these root traits such as structural, physiological, molecular, hydraulic, anatomical, and plasticity, which are important to consider together, with architectural changes, when developing drought resilient crop varieties. In addition, it describes the significance of root contribution in improving soil structure and water holding capacity and its implication on long-term resilience to drought. In addition, various drought adaptive root ideotypes of monocot and dicot crops are compared and proposed for given agroclimatic conditions. Overall, this review provides a broader perspective of understanding root structural, physiological, and molecular regulators, and describes the considerations for simultaneously integrating multiple traits for drought tolerance and crop improvement, under specific growing environments. Full article

The intrusion of weeds into fertile areas has resulted in significant global economic and environmental impacts on agricultural production systems and native ecosystems, hence without ongoing and repeated management actions, the maintenance or restoration of these systems will become increasingly challenging. The establishment of herbicide resistance in many species and unwanted pollution caused by synthetic herbicides has ushered in the need for alternative, eco-friendly sustainable management strategies, such as the use of bioherbicides. Of the array of bioherbicides currently available, the most successful products appear to be sourced from fungi (mycoherbicides), with at least 16 products being developed for commercial use globally. Over the last few decades, bioherbicides sourced from bacteria and plant extracts (such as allelochemicals and essential oils), together with viruses, have also shown marked success in controlling various weeds. Despite this encouraging trend, ongoing research is still required for these compounds to be economically viable and successful in the long term. It is apparent that more focused research is required for (i) the improvement of the commercialisation processes, including the cost-effectiveness and scale of production of these materials; (ii) the discovery of new production sources, such as bacteria, fungi, plants or viruses and (iii) the understanding of the environmental influence on the efficacy of these compounds, such as atmospheric CO₂, humidity, soil water stress, temperature and UV radiation. Full article

Understanding how fertilizer application (particularly N, the most used chemical fertilizer worldwide) interacts with soil microbes is important for the development of best management practices that target improved microbial activity to enhance sustainable food production. This study was conducted to determine whether urea N rate and time of application to maize (Zea mays) influenced soil enzyme activity. Enzyme activity was determined by monitoring fluorescein diacetate (FDA) hydrolysis, ß-glucosidase, acid-phosphomonoesterase, and arylsulfatase activities. Experiments were conducted from 2014 through 2016 to compare single (fall or spring applications) and split applications of N at varying N rates under irrigation (Becker) and rainfed conditions (Lamberton and Waseca) in MN, USA. Nitrogen rates varied by location and were based on University of Minnesota guidelines. Soil samples were collected seven times each season. Nitrogen application split into two applications increased FDA activity by 10% compared with fall and spring applied N at Waseca. Fall or spring N application decreased arylsulfatase activity by 19% at Becker and by between 13% and 16% at Lamberton. ß-Glucosidase and acid-phosphomonoesterase activities were unaffected by N application. Sampling time and year had the greatest impact on enzyme activity, but the results varied by location. A negative linear relationship occurred between FDA and ß-glucosidase activity at all three sites. In summary, urea N application had small effects on enzyme activity at the sites studied, suggesting that some form of organic N could be more important than the ammonium provided by urea. Full article

The genus Viola (Violaceae) is among the 40–50 largest genera among angiosperms, yet its taxonomy has not been revised for nearly a century. In the most recent revision, by Wilhelm Becker in 1925, the then-known 400 species were distributed among 14 sections and numerous unranked groups. Here, we provide an updated, comprehensive classification of the genus, based on data from phylogeny, morphology, chromosome counts, and ploidy, and based on modern principles of monophyly. The revision is presented as an annotated global checklist of accepted species of Viola, an updated multigene phylogenetic network and an ITS phylogeny with denser taxon sampling, a brief summary of the taxonomic changes from Becker’s classification and their justification, a morphological binary key to the accepted subgenera, sections and subsections, and an account of each infrageneric subdivision with justifications for delimitation and rank including a description, a list of apomorphies, molecular phylogenies where possible or relevant, a distribution map, and a list of included species. We distribute the 664 species accepted by us into 2 subgenera, 31 sections, and 20 subsections. We erect one new subgenus of Viola (subg. Neoandinium, a replacement name for the illegitimate subg. Andinium), six new sections (sect. Abyssinium, sect. Himalayum, sect. Melvio, sect. Nematocaulon, sect. Spathulidium, sect. Xanthidium), and seven new subsections (subsect. Australasiaticae, subsect. Bulbosae, subsect. Clausenianae, subsect. Cleistogamae, subsect. Dispares, subsect. Formosanae, subsect. Pseudorupestres). Evolution within the genus is discussed in light of biogeography, the fossil record, morphology, and particular traits. Viola is among very few temperate and widespread genera that originated in South America. The biggest identified knowledge gaps for Viola concern the South American taxa, for which basic knowledge from phylogeny, chromosome counts, and fossil data is virtually absent. Viola has also never been subject to comprehensive anatomical study. Studies into seed anatomy and morphology are required to understand the fossil record of the genus. Full article

The application of biostimulants in agriculture is considered an economically and ecologically acceptable and, above all, a sustainable method of cultivation of field crops. This study aimed to investigate the impact of biostimulating agents on the production and growth parameters of the sugar beet. In 2018 and 2019, an experiment was conducted in which the effect of four types of treatment (B0–B3) on two varieties of sugar beet (Alpaca, Gorila) was observed. The results show that the beets treated with treatment type B3 (combination of humic acids, essential amino acids, biopolymers, and soil bacteria) had the significantly highest yield of roots compared with the control type. However, parameters such as sugar content, polarized sugar yield, white sugar content, and white sugar yield were the highest in condition B2, treated with an agent containing soil bacteria. Furthermore, biostimulants positively affected the leaf area index, with significant growth observed, especially in condition B3. Another important finding was that in the interaction analysis, the biostimulants had positive effects in dry conditions and on elevated values of traits of Alpaca variety caused by treatment in condition B2. In terms of relationships between individual parameters, an interesting finding was that there was only a weak relationship between root yield and sugar content (Rs = 0.0715), which indicates that biostimulants increase production size while maintaining or increasing its quality. Full article

The strawberry fruit contains abundant polyphenols, such as anthocyanins, flavan-3-ol, and ellagitannin. Polyphenol enrichment improves the quality of strawberries and leads to a better understanding of the polyphenol induction process. We measured the total polyphenol content of strawberry fruits under different growth conditions, developmental stages, and treatment conditions during pre-harvest and post-harvest periods. High fruit polyphenol content was observed in cold treatment, which was selected for further analysis and optimization. A transcriptome analysis of cold-treated fruits suggested that the candidate components of polyphenols may exist in the phenylpropanoid pathway. Coverage with a porous film bag excluded the effects of drought stress and produced polyphenol-rich strawberry fruits without affecting quality or quantity. The degree of stress was assessed using known stress indicators. A rapid accumulation of abscisic acid was followed by an increase in superoxide dismutase and DPPH (2,2-Diphenyl-1-picrylhydrazyl) activity, suggesting that the strawberry fruits responded to cold stress immediately, reaching the climax at around 6 days, a trend consistent with that of polyphenol content. These findings enhance our understanding of the mechanism of post-harvest polyphenol accumulation and the value of strawberries as a functional food. Full article

The dried Glechoma hederacea L. herb has a long history of use in traditional medicine. Its therapeutic potential is related to the presence of phenolic compounds. To optimize extraction efficiency the effect of the use of different techniques (HRE—heat reflux extraction, I/ME—infusion combined with maceration, UE—sonication and SE—Soxhlet extraction), various solvents (water and ethanol) and processing time (15 min to 2 h) on phenolics content was investigated. The HPLC method was applied to determine and compare the content of phenolic acids (rosmarinic, chlorogenic, protocatechuic) and flavonoids (rutin, isoquercetin) in the extracts. Furthermore, the cytotoxic activity of the extracts was examined for the first time against human cancer and normal cells of skin origin (A375, HTB140, HaCaT) and gastrointestinal origin (Caco-2 and HT-29, HepG2). In addition, the antioxidant potential was evaluated using the DPPH and FRAP method. The I/ME-water and HRE/ethanol procedures turned out to be optimal for obtaining extracts of dried G. hederacea L. herb rich in bioactive phenolics. These extracts exhibited high antioxidant activity, correlated with the content of the compounds analyzed. Furthermore, the extracts of the dried Glechoma herb were not toxic to normal human cells, indicating its safe use both internally and externally. Full article

The extensive use of synthetic chemical fertilizers is associated with environmental pollution and soil degradation. In addition, the high costs of these fertilizers necessitate the search for alternative, eco-friendly and safe natural sources of phytonutrients. The liquid extracted from moringa (Moringa oleifera Lam.) leaves has been used in agriculture to improve the growth and productivity of several crops. The efficacy of moringa leaf extract (MLE) is attributed to its high content of mineral nutrients, protein, vitamins, sugars, fiber, phenolics and free proline. In addition, MLE contains significant amounts of phytohormones, such as auxins, cytokinins and gibberellins. Furthermore, MLE is a valuable product promoting seed germination, plant growth and deeper root development, delaying fruit senescence and increasing the yield and quality of crops grown under normal or stressful conditions. Here, we review the research on MLE as a biostimulant to enhance crop growth and productivity. Moreover, we emphasize its possible introduction to smallholder farming systems to provide phytonutrients, and we further highlight research gaps in the existing knowledge regarding MLE application. Generally, MLE is an inexpensive, sustainable, eco-friendly and natural biostimulant that can be used to improve the growth and productivity attributes of various crops under non-stressful and stressful conditions. Full article

Haberlea rhodopensis is a unique desiccation-tolerant angiosperm that also survives winter frost. As, upon freezing temperatures, H. rhodopensis desiccates, the taxon is proposed to survive low temperature stress using its desiccation tolerance mechanisms. To reveal the validity of this hypothesis, we analyzed the structural alterations and organization of photosynthetic apparatus during the first hours of recovery after drought- and freezing-induced desiccation. The dynamics of the ultrastructure remodeling in the mesophyll cells and the restoration of the thylakoid membranes shared similarities independent of the reason for desiccation. Among the most obvious changes in thylakoid complexes, the proportion of the PSI-LHCII complex strongly increased around 70% relative water content (RWC), whereas the proportion of Lhc monomers decreased from the beginning of rehydration. We identified enhanced levels of cyt b₆f complex proteins that contributed to the enhanced electron flow. The high abundance of proteins related to excitation energy dissipation, PsbS, Lhcb5, Lhcb6 and ELIPs, together with the increased content of dehydrins contributed to the preservation of cellular integrity. ELIP expression was maintained at high levels up to 9 h into recovery. Although the recovery processes from drought- and freezing-induced desiccation were found to be similar in progress and time scale, slight variations indicate that they are not identical. Full article

Tobamoviruses are among the most well-studied plant viruses and yet there is still a lot to uncover about them. On one side of the spectrum, there are damage-causing members of this genus: such as the tobacco mosaic virus (TMV), tomato brown rugose fruit virus (ToBRFV) and cucumber green mottle mosaic virus (CGMMV), on the other side, there are members which cause latent infection in host plants. New technologies, such as high-throughput sequencing (HTS), have enabled us to discover viruses from asymptomatic plants, viruses in mixed infections where the disease etiology cannot be attributed to a single entity and more and more researchers a looking at non-crop plants to identify alternative virus reservoirs, leading to new virus discoveries. However, the diversity of these interactions in the virosphere and the involvement of multiple viruses in a single host is still relatively unclear. For such host–virus interactions in wild plants, symptoms are not always linked with the virus titer. In this review, we refer to latent infection as asymptomatic infection where plants do not suffer despite systemic infection. Molecular mechanisms related to latent behavior of tobamoviruses are unknown. We will review different studies which support different theories behind latency. Full article

Leaf nutrient content and its stoichiometric relationships (N/P ratio) are essential for photosynthesis and plant growth and development. Previous studies on leaf nutrient-related functional traits have mainly focused on the species level and regional scale, but fewer studies have investigated the distribution patterns of the leaf N and P contents (LN, LP) and N/P ratios (N/P) in communities and their controlling factors at a large scale; therefore, we used LN, LP, and N/P data at 69 sites from 818 forests in China. The results showed significant differences (p < 0.05) in the LN, LP, and N/P at different life forms (tree, shrub, and herb). Neither LN, LP, nor N/P ratios showed significant patterns of latitudinal variation. With the increase in temperature and rainfall, the LN, LP, and leaf nutrient contents increased significantly (p < 0.001). Across life forms, LN at different life forms varied significantly and was positively correlated with soil P content (p < 0.001). The explanatory degree of climatic factors in shaping the spatial variation patterns of LN and N/P was higher than that of the soil nutrient factors, and the spatial variation patterns of the leaf nutrient traits of different life forms were shaped by the synergistic effects of climatic factors and soil nutrient factors. Full article

Light stress signalling in algae and plants is partially orchestrated by singlet oxygen (¹O₂), a reactive oxygen species (ROS) that causes significant damage within the chloroplast, such as lipid peroxidation. In the vicinity of the photosystem II reaction centre, a major source of ¹O₂, are two β-carotene molecules that quench ¹O₂ to ground-state oxygen. ¹O₂ can oxidise β-carotene to release β-cyclocitral, which has emerged as a ¹O₂-mediated stress signal in the plant Arabidopsis thaliana. We investigated if β-cyclocitral can have similar retrograde signalling properties in the unicellular alga Chlamydomonas reinhardtii. Using RNA-Seq, we show that genes up-regulated in response to exogenous β-cyclocitral included CAROTENOID CLEAVAGE DIOXYGENASE 8 (CCD8), while down-regulated genes included those associated with porphyrin and chlorophyll anabolism, such as tetrapyrrole-binding protein (GUN4), magnesium chelatases (CHLI1, CHLI2, CHLD, CHLH1), light-dependent protochlorophyllide reductase (POR1), copper target 1 protein (CTH1), and coproporphyrinogen III oxidase (CPX1). Down-regulation of this pathway has also been shown in β-cyclocitral-treated A. thaliana, indicating conservation of this signalling mechanism in plants. However, in contrast to A. thaliana, a very limited overlap in differential gene expression was found in β-cyclocitral-treated and ¹O₂-treated C. reinhardtii. Furthermore, exogenous treatment with β-cyclocitral did not induce tolerance to ¹O₂. We conclude that while β-cyclocitral may down-regulate chlorophyll synthesis, it does not seem to contribute to ¹O₂-mediated high light stress signalling in algae. Full article

The Ilyonectria radicicola species complex (A.A. Hildebr.) A. Cabral and Crous 2011 contains species of soilborne necrotrophic plant pathogens. The most aggressive to ginseng roots is I. mors-panacis, whereas I. robusta, I. crassa, I. panacis and I. radicicola are less aggressive. Infected ginseng roots show orange-red to black-brown lesions that can expand into a severe root rot, known as disappearing root rot, where only epidermal root tissue remains. Leaves become red-brown with wilting, and stems can have vascular discoloration with black-brown lesions at the base. Less aggressive Ilyonectria species trigger jasmonic acid (JA)-related defenses inducing host ginsenosides, pathogenesis-related (PR) proteins, wound periderm, and cell wall thickening. In contrast, I. mors-panacis triggers reactive oxygen species (ROS) and salicylic acid (SA) production but suppresses JA-related defenses and ginsenoside accumulation. It is also able to suppress SA-related PR protein production. Virulence factors include potential effectors that may suppress PAMP (Pathogen Associated Molecular Patterns) triggered immunity (PTI), polyphenoloxidases, Hsp90 inhibitors, siderophores and cell-wall-degrading enzymes, such as pectinases. Overall, I. mors-panacis appears to be more aggressive because it can suppress JA and SA-related PTI allowing for more extensive colonization of ginseng roots. While many possible mechanisms of host resistance and pathogen virulence mechanisms have been examined, there is a need for using genetic approaches, such as RNAi silencing of genes of Panax or Ilyonectria, to determine their importance in the interaction. Full article

There is an increasing demand for sweet melon (Cucumis melo L.) fruit in fruit and vegetable markets due to its nutritional content, resulting in different cultivars being grown in different production systems. This study evaluated the nutritional and phytochemical contents of soilless-grown cantaloupe and honeydew sweet melon cultivars at harvest and postharvest. At harvest, vitamin C and β-carotene concentrations were higher in orange-fleshed (cantaloupe) cvs. Magritte, Divine, Majestic, Cyclone, MAB 79001, E25F.00185, E25F.00075 and Adore, compared to green-fleshed (honeydew) cvs. Honey Brew and Honey Star. The zinc (Zn), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) contents were higher in orange-fleshed compared to green-fleshed cultivars. Total phenolics content (TPC) in cv. E25F.00075 was the highest (2.87 mg GAE∙g⁻¹ dry weight). A significant, positive, correlation occurred between β-carotene and Zn, P, K, Ca and Mg contents. Postharvest storage duration affected TPC and total soluble solid content. The interaction of cultivar and postharvest storage duration affected flavonoid, vitamin C and β-carotene contents, free radical scavenging activity and fruit juice pH. Vitamin C and β-carotene contents decreased with increased postharvest storage duration while flavonoid content increased. The cantaloupe cultivars performed significantly better compared to the honeydew cultivars as evident in their high mineral element content, and vitamin C and β-carotene concentrations. Selection of appropriate cultivars in a production system should consider variation in nutritional traits of cultivars and postharvest storage duration. Soilless production of sweet melon cultivars in tunnels offers a viable alternative to open field to produce high-quality melons at harvest and postharvest. Full article