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The root system is vital for anchorage, mobilizing water and nutrients and symbiosis with soil microbes, which influence adaptation and crop performance. However, root traits are not widely used in crop variety development because root phenotyping is difficult and there is limited understanding of the genetics of root traits. The available genetic variation and emerging root phenotyping and genotyping technologies present opportunities for integrating root traits in breeding. Selection efficiency for root traits can be enhanced by integrating shovelomics, digital imaging, crop modelling and gene sequencing systems. Therefore, the objectives of this review are to discuss critical root traits and their vital functions, genetic variation present for root traits, opportunities and challenges in root phenotyping and integration of genomic tools in breeding for improved root systems. The information presented in the paper will guide crop breeders in developing a new generation of crop varieties with desirable yield and root traits. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.) plays an important role in livestock production in most regions of the world, but the quantity and quality of alfalfa have been critically affected by drought events in recent years. Thus, quantifying the efficacy of widely used strategies, irrigation methods and fertilization that are aimed at improving drought resistance in alfalfa is a worthy topic that has been addressed in a variety of ways using both field observations and simulation models. Although such strategies play a critical role in climate change adaptation, the global patterns of these strategies in a changing world remain elusive due to regional differences, such as drought features, strategy design and environmental conditions. Thus, by using effect size and statistical analyses, we synthesized three variables, namely, alfalfa yield, water use efficiency (WUE) and crude protein (CP), to examine the efficacy of irrigation methods and fertilization in drought areas based on peer‐reviewed papers from 1990 to 2022. Our results showed that increasing drought stress reduces the alfalfa yield (−34.4%) but can increase the WUE (+13.7%). Both yield and WUE showed a negative relationship with the water deficit, but this phenomenon can be improved by using appropriate irrigation. The yield losses of alfalfa can be offset by implementing a fertilization strategy (+22%) under drought stress, especially for phosphate fertilizer. Overall, our results provide some evidence for the climate change adaptation of alfalfa under drought stress and indicate that fertilization is a more effective adaptation to improve alfalfa drought resistance (both yield and WUE, and yield and CP) than the irrigation method, which shows better performance in improving alfalfa WUE. Our synthesis of the effectiveness of irrigation methods and fertilization on alfalfa drought resistance can be used to develop scientific strategies for climate change adaptation for alfalfa and agriculture under climate change. [ABSTRACT FROM AUTHOR]

Background: Use of soil amendments in agriculture is an old practice and with increase in demand of organic agriculture, it is gaining more attention. Work on the quality of the produce more particularly if crop faces any adverse situation like drought are scarce. This paper provides a comparative assessment of organic (farm yard manure) and inorganic (biochar) soil amendments on grain quality of grass pea (Lathyrus sativus L.) when crop faces drought. Different grain quality parameters were studied along with crop health and grain yield under the application of soil amendments during drought. Results: Biochar and farm yard manure (FYM) lowered drought‐induced leaf water potential (upto 22%) and root nitrate reductase activity (by 62% and 67% respectively). Both inorganic and organic soil amendments improved in vitro protein digestibility (up to 16% and 37% respectively). Whereas higher grain phytic acid content (increased up to 40%) was noted from application of organic amendment (FYM) compared to inorganic (16% increase in biochar treated plots). Protein yield is enhanced (8%) under the application of Biochar‐enhanced protein yield by 8% when crops experienced drought at vegetative stage, whereas FYM reduced it by 9% under the same situation. Conclusion: Tested soil amendments can improve grain quality of grass pea. However, they were not equally efficient when the crop experienced drought at either stage of growth. Thus, screening of soil amendment is important when added under stressful situation like drought to ascertain better grain quality for consumers. [ABSTRACT FROM AUTHOR]

Sunflower seeds (hybrid Luka) were primed with water (hydropriming) or sodium hydrosulphide (NaHS) solutions (0.1, 0.5, 1.0 and 1.5 mM NaHS) and subsequently dried to initial moisture content. Unprimed (control) and primed seeds were germinated in a growth chamber on paper towels moistened with water or polyethylene glycol (PEG) 6000 solutions (2.5, 5.0 and 10%), mimicking different drought stress levels. To evaluate the response of the primed seeds to drought in the germination stage, the germination energy (GE), germination rate (SG), seedling fresh mass (SW), hydrogen peroxide and free proline content (PRO), as well as lipid peroxidation rate (malondialdehyde; MDA) were established. The results show strong effects of the imposed drought stress and the metabolic response to oxidative stress through lower germinability and proline accumulation in seedlings. NaHS priming showed some positive effects on seed germination depending on stress level and the concentration of NaHS. Sunflower seeds were also germinated in pots filled with soil, at optimal (70% of field water capacity [FWC 70%]) and drought conditions (FWC 30%), in natural outdoors conditions. When plantlets developed the first pair of leaves, the number of plants (emergence rate [ER]), shoot mass (SM) and leaves mass (LM) were determined, as well as the total activities of catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and dehydroascorbate reductase (DHAR). There was a significant influence of an interaction between drought stress and priming, whereas drought stress inhibited plant emergence and early growth (SW and LW), and strong antioxidative enzymatic response to drought stress was clearly established in the leaves. Although seed priming showed some influence on enzyme activities, it was mostly related to seed hydropriming effects, while NaHS seed priming was less effective, influencing only DHAR. Altogether, the results imply that sunflower seed priming with NaHS may not have a prolonged impact on the antioxidative defence mechanism based on CAT and ascorbate/glutathione cycle during sunflower early growth in drought conditions. [ABSTRACT FROM AUTHOR]

Isoprene concentrations were measured at four heights below, within, and above the forest canopy in Wytham Woods (United Kingdom) throughout the summer of 2018 using custom‐built gas chromatographs (the iDirac). These observations were complemented with selected ancillary variables, including air temperature, photosynthetically active radiation, occasional leaf gas exchange measurements, and satellite retrievals of normalized difference vegetation and water indices. The campaign overlapped with a long and uninterrupted heatwave accompanied by moderate drought. Peak isoprene concentrations during the heatwave‐drought were up to a factor of 4 higher than those before or after. Higher temperatures during the heatwave could not account for all the observed isoprene; the enhanced abundances correlated with drought stress. Leaf‐level emissions confirmed this and also included compounds associated with ecosystem stress. This work highlights that a more in‐depth understanding of the effects of drought stress is required to better characterize isoprene emissions. Plain Language Summary: Plants emit a number of volatile organic compounds into the atmosphere as a response to environmental stimuli such as temperature and incoming sunlight. Once emitted, these compounds undergo chemical processes that can affect local air quality (for instance, contributing to the formation of pollutants such as ground‐level ozone) and climate (by contributing to the formation of aerosol particles). Numerical models have been developed to successfully simulate volatile emissions under most environmental conditions. However, one notable exception is during extreme weather events such as heatwaves and droughts, where current models appear inadequate. In this paper, we present a unique data set consisting of continuous measurements of isoprene, the main volatile emission from vegetation, during the summer of 2018 in a UK temperate forest. A prolonged heatwave and drought affected the United Kingdom that summer. We report unusually high levels of isoprene and show that higher temperatures during the heatwave cannot account for all the observed isoprene. Our analysis shows that ecosystem stress brought about by moderate drought correlates with the enhanced isoprene. This work enables an improved description of isoprene emissions under extreme events (droughts) that are predicted to become more frequent in the near future as a consequence of global change. Key Points: Isoprene concentrations were monitored for a whole growing season in a temperate forest in the United Kingdom before, during, and after the 2018 heatwaveIsoprene abundances during the heatwave increased by up to 400%, and stress‐related sesquiterpenes were observed during the heatwaveHigher temperatures in the heatwave cannot account for all the enhanced isoprene abundances, which correlate to drought stress [ABSTRACT FROM AUTHOR]

Global water scarcity and extreme weather intensify drought stress, significantly reducing cotton yield and quality worldwide. Drought treatments are conducted using a population of chromosome segment substitution lines generated from E22 (G. hirsutum) and 3–79 (G. barbadense) as parental lines either show superior yields or fiber quality under both control and drought conditions. Fourteen datasets, covering 4 yields and 4 quality traits, are compiled and assessed for drought resistance using the drought resistance coefficient (DRC) and membership function value of drought resistance (MFVD). Genome‐wide association studies, linkage analysis, and bulked segregant analysis are combined to analyze the DR‐related QTL. A total of 121 significant QTL are identified by DRC and MFVD of the 8 traits. CRISPR/Cas9 and virus‐induced gene silencing techniques verified DRR1 and DRT1 as pivotal genes in regulating drought resistant of cotton, with hap3‐79 exhibiting greater drought resistance than hapE22 concerning DRR1 and DRT1. Moreover, 14 markers with superior yield and fiber quality are selected for drought treatment. This study offers valuable insights into yield and fiber quality variations between G. hirsutum and G. barbadense amid drought, providing crucial theoretical and technological backing for developing cotton varieties resilient to drought, with high yield and superior fiber quality. [ABSTRACT FROM AUTHOR]

Enhancing crop drought tolerance is crucial for food security amid climate change. This study examines how 5‐aminolevulinic acid (ALA) and hydrogen sulfide (H2S) can improve drought resilience in tomato plants, which are essential for sustainable food production. Drought stress was induced using 12% PEG‐6000. Plants were pre‐treated with 25 mg L−1 ALA and 0.1 mg L−1 hypotaurine (HT), followed by 0.2 mM sodium hydrosulfide (NaHS) treatment to assess the effects on plant physiological effects over 10 days. Drought stress reduced plant dry weight, chlorophylls (a and b), Fv/Fm, leaf water potential, and relative water content, while increasing glycine betaine (GB) and proline levels. Additionally, drought stress elevated NADPH oxidase (NOX) and glycolate oxidase (GOX) activities, inducing oxidative stress and membrane damage. ALA and NaHS enhanced plant growth, photosynthesis, proline, GB, ALA content, ATP synthase, and ATPase activities, while mitigating NOX and GOX activities, thereby reducing O2·−$$ {\mathrm{O}}_2^{\cdotp -} $$ and H2O2 radicals. ALA alone boosted L‐DES activity, promoting H2S accumulation. However, ALA + HT reduced H2S levels, compromising ALA's efficacy. NaHS with ALA + HT reinstated positive effects by restoring H2S levels. Biochemical assays confirmed ALA and NaHS promoted H2S accumulation, bolstering antioxidants, mitigating lipid peroxidation, suggesting their drought resilience potential in tomatoes. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) has been studied for its potential to enhance stress tolerance in plant systems, but the role of hydrogen sulfide (H2S) in GSH‐induced water stress tolerance in sweet pepper (Capsicum annuum L.) is still under investigation. This study explores how H2S and GSH modulate water stress tolerance in pepper plants, addressing a research gap. The joint effect of sodium hydrosulfide (NaHS), a donor of H2S, and GSH on water stress tolerance was determined through pre‐treatment with the H2S scavenger 0.1 mM hypotaurine (HT). Pepper seedlings were sprayed with 1.0 mM GSH or GSH + 0.2 mM NaHS once a week, with soil moisture content set at 80% and 40% for full irrigation and water stress conditions for a duration of 2 weeks. The results showed that water stress significantly reduced total plant dry weight, chlorophyll a and b content, Fv/Fm, leaf water potential, and relative water content by 50%, 56%, 33%, 27%, 52%, and 34%, while increasing hydrogen peroxide (H2O2), proline, and H2S levels by 152%, 134%, and77%, respectively. Treatment with GSH and NaHS reduced water stress‐induced H2O2 production and improved plant growth, photosynthetic traits, proline, and the activity of L‐cysteine desulfhydrase (L‐DES), leading to the generation of H2S content. GSH reduced NADPH oxidase (NOX), superoxide dismutase (SOD), and H2O2 but increased glutathione peroxidase (GPX) activities. The interaction of NaHS and GSH led to further reductions in NOX, SOD, and H2O2 values but increased GPX activity. The combined GSH and NaHS treatment increased nitric oxide (NO) production but decreased the activity of S‐nitrosoglutathione reductase (GSNOR), potentially accelerating S‐nitrosylation. Hypotaurine negated the positive impacts of GSH on water stress tolerance by reducing H2S concentration in pepper plants, but this was corrected by the concurrent application of NaHS and GSH + HT. Therefore, water stress tolerance requires H2S. [ABSTRACT FROM AUTHOR]

Improving seed germination under drought stress has the potential to increase crop yield in dry direct‐seeded rice. In this study, a genome‐wide association study (GWAS) was conducted to determine the genetic basis of seed germination under drought stress in a panel of 165 rice accessions using a multi‐locus compressed variance‐component mixed model, 3VmrMLM. A total of 33 quantitative trait nucleotides (QTNs) were identified in association with drought tolerance during seed germination. Around these QTNs, eight were found to be co‐localized with known drought‐related genes. Furthermore, a causal candidate gene, OsGA2ox5, which encodes a gibberellin (GA) 2‐oxidase, was identified for QTN‐Chr07_242906 by integrating linkage disequilibrium (LD) analysis and gene expression analysis. Knockout mutation of OsGA2ox5 resulted in delayed seed germination and retarded seedling growth under drought stress. RNA‐seq analysis revealed that OsGA2ox5 regulates drought tolerance during seed germination mainly by modulating carbohydrate metabolism. Additionally, a non‐synonymous coding variant in OsGA2ox5, SNP‐Chr07_218893, was found to be strongly associated with drought tolerance level during seed germination. These findings provide valuable information for further exploration of novel drought‐related genes and genetic improvement of rice drought tolerance in the future. [ABSTRACT FROM AUTHOR]

The symbiotic synergy between proteome shifts in plants and microbial colonization orchestrates adaptive responses. This thorough review delves into the less explored domain of proteomic and metabolomic changes triggered by drought stress, shedding light on how they are influenced by interactions with microbiota. Notably, microbial mediation at the crossroads of hormone signaling, proteomic and metabolomic dynamics in drought adaptation emerges as a crucial focal point. Understanding the regulatory mechanisms that orchestrate these complex interactions offers a holistic view of the molecular foundation underlying a plant's ability to endure water scarcity. The insights gained from this exploration hold the potential to reshape agricultural practices and enhance drought‐tolerance through microbiota‐mediated mechanisms, supported by proteomic and metabolomic insights. As this review seamlessly integrates the latest developments in understanding drought stress responses, microbiota dynamics, proteomics and metabolomic, it reveals the interconnected molecular basis that underlies these aspects. Specifically, the review emphasizes the crucial role of microbial mediation at the crossroads of hormone signaling, proteomic and metabolomic dynamics during drought adaptation. This enhanced understanding of the intricate interactions among these components presents new opportunities for envisioning sustainable agricultural approaches in the face of the escalating challenges presented by intensifying drought scenarios. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, we introduce an ecologically relevant measure of drought stress and its relationship with vegetation characteristics. We used process-based simulations of reference drought stress on inclined surfaces with different soil type, slope, and aspect to get an insight in the drought statistics that explain small-scale differences in vegetation characteristics. Mean intensity, duration, and frequency of drought events are commonly integrated into the so-called 'dynamic drought stress' TSdyn. We introduce a simple, physiology-based alternative measure of drought stress TSupp, based on the finding that plants respond to extremes rather than to mean intensities of stress events. Using extremes instead of mean intensities makes information on duration and frequency of stress events superfluous. We show that compared with TSdyn, TSupp (i) is a better predictor of the fraction of xerophytes within a vegetation plot, (ii) is simple, transparent, and easy to interpret as only the uppermost intensities are involved, i.e. minimum parameters are needed, and (iii) does not involve empirical parameters, as are used in TSdyn. Focusing on extremes rather than on means is especially important in predicting climate change effects, as especially these extremes are predicted to increase due to climate change. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Drought tolerance is a comprehensive quantitative trait that is being understood further at the molecular genetic level. Abscisic acid (ABA) is the main drought-induced hormone that regulates the expression of many genes related to drought responses. 9-cis-epoxycarotenoid dioxygenase (NCED3) is thought to be a key enzyme in ABA biosynthesis. In this paper, we measured the ABA content increase under drought stress, and sequenced and compared the sequence of AtNCED3 among 22 Arabidopsis thaliana accessions. The results showed that the fold of ABA content increase under drought stress was highly variable among these accessions. High density single nucleotide polymorphism (SNP) and insertion/deletion (indel) were found in the AtNCED3 region, on average one SNP per 87.4 bp and one indel per 502 bp. Nucleotide diversity was significantly lower in the coding region than that in non-coding regions. The results of an association study withanova analysis suggested that the 274th site (P↔S) and the 327th site (P↔R) amino acid variations might be the cause of ABA content increase of 163av accession under drought stress. [ABSTRACT FROM AUTHOR]

Most thermal methods for the study of drought responses in plant leaves are based on the calculation of ‘stress indices’. This paper proposes and compares three main extensions of these for the direct estimation of absolute values of stomatal conductance to water vapour ( gs) using infrared thermography (IRT). All methods use the measured leaf temperature and two environmental variables (air temperature and boundary layer resistance) as input. Additional variables required, depending on the method, are the temperatures of wet and dry reference surfaces, net radiation and relative humidity. The methods were compared using measured gs data from a vineyard in Southern Portugal. The errors in thermal estimates of conductance were of the same order as the measurement errors using a porometer. Observed variability was also compared with theoretical estimates of errors in estimated gs determined on the basis of the errors in the input variables (leaf temperature, boundary layer resistance, net radiation) and the partial derivatives of the energy balance equations used for the gs calculations. The full energy balance approach requires accurate estimates of net radiation absorbed, which may not be readily available in field conditions, so alternatives using reference surfaces are shown to have advantages. A new approach using a dry reference leaf is particularly robust and recommended for those studies where the specific advantages of thermal imagery, including its non-contact nature and its ability to sample large numbers of leaves, are most apparent. Although the results suggest that estimates of the absolute magnitude of gs are somewhat subjective, depending on the skill of the experimenter at selecting evenly exposed leaves, relative treatment differences in conductance are sensitively detected by different experimenters. [ABSTRACT FROM AUTHOR]

The natural variation between Arabidopsis (Arabidopsis thaliana) ecotypes Columbia (Col) and Landsberg erecta (Ler) strongly affects abscisic acid (ABA) signalling and drought tolerance. Here, we report that the cysteine‐rich receptor‐like protein kinase CRK4 is involved in regulating ABA signalling, which contributes to the differences in drought stress tolerance between Col‐0 and Ler‐0. Loss‐of‐function crk4 mutants in the Col‐0 background were less drought tolerant than Col‐0, whereas overexpressing CRK4 in the Ler‐0 background partially to completely restored the drought‐sensitive phenotype of Ler‐0. F1 plants derived from a cross between the crk4 mutant and Ler‐0 showed an ABA‐insensitive phenotype with respect to stomatal movement, along with reduced drought tolerance like Ler‐0. We demonstrate that CRK4 interacts with the U‐box E3 ligase PUB13 and enhances its abundance, thus promoting the degradation of ABA‐INSENSITIVE 1 (ABI1), a negative regulator of ABA signalling. Together, these findings reveal an important regulatory mechanism for modulating ABI1 levels by the CRK4‐PUB13 module to fine‐tune drought tolerance in Arabidopsis. Summary statement: CRK4, contributing to the drought stress difference between Col‐0 and Ler, interacts with and enhances the protein levels of the U‐box E3 ligase PUB13, which promotes the degradation of ABI1 (ABA‐INSENSITIVE 1), thus positively regulating ABA‐mediated stomatal movements and drought stress tolerance. [ABSTRACT FROM AUTHOR]

Premise: Higher temperatures across the globe are causing an increase in the frequency and severity of droughts. In agricultural crops, this results in reduced yields, financial losses, and increased food costs at the supermarket. Root growth maintenance in drying soils plays a major role in a plant's ability to survive and perform under drought, but phenotyping root growth is extremely difficult due to roots being under the soil. Methods and Results: RootBot is an automated high‐throughput phenotyping robot that eliminates many of the difficulties and reduces the time required for performing drought‐stress studies on primary roots. RootBot simulates root growth conditions using transparent plates to create a gap that is filled with soil and polyethylene glycol (PEG) to simulate low soil moisture. RootBot has a gantry system with vertical slots to hold the transparent plates, which theoretically allows for evaluating more than 50 plates at a time. Software pipelines were also co‐opted, developed, tested, and extensively refined for running the RootBot imaging process, storing and organizing the images, and analyzing and extracting data. Conclusions: The RootBot platform and the lessons learned from its design and testing represent a valuable resource for better understanding drought tolerance mechanisms in roots, as well as for identifying breeding and genetic engineering targets for crop plants. [ABSTRACT FROM AUTHOR]

Drought is a major abiotic stress that impairs the physiology and development of plants, ultimately leading to crop yield losses. Drought tolerance is a complex quantitative trait influenced by multiple genes and metabolic pathways. However, molecular intricacies and subsequent morphological and physiological changes in response to drought stress remain elusive. Herein, we combined morpho‐physiological and comparative RNA‐sequencing analyses to identify core drought‐induced marker genes and regulatory networks in the barley cultivar 'Giza134'. Based on field trials, drought‐induced declines occurred in crop growth rate, relative water content, leaf area duration, flag leaf area, concentration of chlorophyll (Chl) a, b and a + b, net photosynthesis, and yield components. In contrast, the Chl a/b ratio, stoma resistance, and proline concentration increased significantly. RNA‐sequence analysis identified a total of 2462 differentially expressed genes (DEGs), of which 1555 were up‐regulated and 907 were down‐regulated in response to water‐deficit stress (WD). Comparative transcriptomics analysis highlighted three unique metabolic pathways (carbohydrate metabolism, iron ion binding, and oxidoreductase activity) as containing genes differentially expressed that could mitigate water stress. Our results identified several drought‐induced marker genes belonging to diverse physiochemical functions like chlorophyll concentration, photosynthesis, light harvesting, gibberellin biosynthetic, iron homeostasis as well as Cis‐regulatory elements. These candidate genes can be utilized to identify gene‐associated markers to develop drought‐resilient barley cultivars over a short period of time. Our results provide new insights into the understanding of water stress response mechanisms in barley. [ABSTRACT FROM AUTHOR]

In the natural environment, plants are subjected to simultaneous or sequential presence of various abiotic and/or biotic stresses, including soil compaction and soil drought. The effects of these stresses tested separately are relatively well understood, but still little is known about their simultaneous effects on plants. Our research involved four single hybrids of maize differing in their degree of susceptibility to soil compaction and drought. We investigated the effects of low and high soil compaction under optimal irrigation (LI, HI) and under three‐week long soil drought (LD, HD), on the gas exchange (Pn, E, gS, Ci) and chlorophyll fluorescence parameters (F0, Fm, Fv, Fv/Fm), total leaf area (LA), leaf greening (SPAD), leaf water deficit (WD), leaf water potential (ψ) and membrane injury (MI). The plants experiencing high soil compaction (HI) showed a decrease in all parameters of gas exchange (Pn, E, gS, Ci), leaf area (LA), leaf greening (SPAD) and the maximal quantum efficiency of PSII (Fv/Fm) in comparison with plants growing in non‐compacted soil (LI). An increase was observed in the other fluorescence parameters, i.e., F0, Fm and Fv and leaf WD, ψ and MI in HI vs. LI variants. In the plants exposed to drought (LD, HD), the changes in the measured traits were greater, especially for the sensitive hybrids P‐8400 and NS‐3023, than for the plants from LI treatment. A significant interaction between the degree of stress susceptibility and relative trait change was observed for practically all of the measured features. Moreover, in the short recovery period after the end of drought, the measured traits in LD and HD plants did not fully return to the control level, especially in the case of the sensitive hybrids (P‐8400 NS‐3023). The physiological reaction of maize hybrids to soil compaction and/or soil drought indicated the genetically determined variability of tolerance to those stresses. Significant correlation between RTC and stress susceptibility indexes (S‐SI) provided suitable criteria for the hybrid selection. Also, our results showed the plasticity and capability of maize hybrids to respond to environmental conditions. [ABSTRACT FROM AUTHOR]

Studies on plant responses to combined abiotic stresses are very limited, especially in major crop plants. The current study evaluated the response of chorismate mutase overexpressor (OxCM) rice line to combined UV light and drought stress.The experiments were conducted in pots in a growth chamber, and data were assessed for gene expression, antioxidant and hormone regulation, flavonoid accumulation, phenotypic variation, and amino acid accumulation.Wild‐type (WT) rice had reduced the growth and vigour, while transgenic rice maintained growth and vigour under combined UV light and drought stress. ROS and lipid peroxidation analysis revealed that chorismate mutase (OsCM) reduced oxidative stress mediated by ROS scavenging and reduced lipid peroxidation. The combined stresses reduced biosynthesis of total flavonoids, kaempferol and quercetin in WT plants, but increased significantly in plants with OxCM. Phytohormone analysis showed that SA was reduced by 50% in WT and 73% in transgenic plants, while ABA was reduced by 22% in WT plants but increased to 129% in transgenic plants. Expression of chorismate mutase regulates phenylalanine biosynthesis, UV light and drought stress‐responsive genes, e.g., phenylalanine ammonia lyase (OsPAL), dehydrin (OsDHN), dehydration‐responsive element‐binding (OsDREB), ras‐related protein 7 (OsRab7), ultraviolet‐B resistance 8 (OsUVR8), WRKY transcription factor 89 (OsWRKY89) and tryptophan synthase alpha chain (OsTSA). Moreover, OsCM also increases accumulation of free amino acids (aspartic acid, glutamic acid, leucine, tyrosine, phenylalanine and proline) and sodium (Na), potassium (K), and calcium (Ca) ions in response to the combined stresses.Together, these results suggest that chorismate mutase expression induces physiological, biochemical and molecular changes that enhance rice tolerance to combined UV light and drought stresses. [ABSTRACT FROM AUTHOR]

At a concentration equivalent to 0.3-1 μM, the norepinephrine solution in which the drought-stressed plants of Lemna paucicostata 441 were immersed for 2 h, induced flowering in L. paucicostata 151. Not only drought stress but also osmotic stress, 5 min on 0.5 M mannitol solution, and heat stress, 5 min on 45-55°C hot water, were effective in producing or releasing a factor capable of activating norepinephrine. Such a putative factor has been designated as 'factor C'. The first supernatant obtained after immediate centrifugation of the homogenate of the plants had only weak factor C activity, but the second supernatant, obtained after a 30-min incubation of the suspension of the first pellet, showed high factor C activity. The water in which Lemna plants subjected to both drought and heat stresses had been immersed for 2 h, showed flower-inducing activity even in the absence of added norepinephrine. [ABSTRACT FROM AUTHOR]

Dehydrins are well known for being expressed in leaves during the course of developmental processes as well as under drought stress, being part of the protective machinery. Moreover, in seed physiology, dehydrins are classified as late embryogenesis-related proteins ( LEA protein), where they are thought to be responsible for persistence and longevity of seeds. Although both topics are a focus of modern plant biology, a direct linkage between these both areas is generally lacking. Based on an alignment of the chain of events, this paper will help to generate understanding that the occurrence of dehydrins in maturing seeds and leaves suffering drought stress is part of the same basic principle: basic principle: dehydrins are expressed in response to water shortage. Unfortunately, the related developmental process in seeds, i.e. maturation drying, has not been adequately considered as a part of this process. As a corresponding implication, the chain of events must be adjusted: the differences in dehydrin expression in orthodox, intermediate and recalcitrant seeds could be directly attributed to the occurrence or absence of maturation drying. The differences in dehydrin expression in orthodox, intermediate and recalcitrant seeds, and thus the differences in longevity, could be attributed to the occurrence or absence of a maturation drying. [ABSTRACT FROM AUTHOR]

Legumes grow in temperate and warm climates, being susceptible to unpredictable episodes of water deficit. This study aimed to evaluate (i) morphology and N‐compound contents in roots and nodules, (ii) N and C contents in shoots and (iii) crop yield in two peanut cultivars with contrasting drought tolerance, inoculated with a reference N‐fixing strain and challenged by water deficit conditions. For that, seeds of two peanut cultivars, Granoleico (sensitive, S) and EC‐98 (tolerant, T) were inoculated with Bradyrhizobium sp. SEMIA6144 and 30 days after sowing, plants were separated into the experimental groups: control, drought stress and drought stress and subsequent rehydration. Although the results obtained on root anatomy and histology revealed differential responses between cultivars, they were not associated with tolerance traits in EC‐98 (T). In contrast, nodules of EC‐98 (T) showed invariable diameter and infection zone upon the exposition to drought stress and rehydration compared to nodules of Granoleico (S) plants exposed to the same treatments. EC‐98 (T) showed invariable contents of C in shoots and of nitrates and ureides in roots and nodules of stressed and rehydrated plants, an increase in total amino acids only in nodules of stressed plants and a small reduction in N‐content (compared with the sensitive cultivar). The status of these variables related to C‐ and N‐metabolism could be associated with an efficient biological nitrogen fixation. Besides, EC‐98 (T) yielded better both in a crop cycle with adequate water supply and in a dry year and the inoculation improved yield in both cultivars. Thus, the inoculation with N‐fixing bacteria is recommended for EC‐98 (T) in seasons with expected drought stress cycles in crops. [ABSTRACT FROM AUTHOR]

Summary: RAD23 (RADIATION SENSITIVE23) proteins are a group of UBL‐UBA (ubiquitin‐like‐ubiquitin‐associated) proteins that shuttle ubiquitylated proteins to the 26S proteasome for breakdown. Drought stress is a major environmental constraint that limits plant growth and production, but whether RAD23 proteins are involved in this process is unclear. Here, we demonstrated that a shuttle protein, MdRAD23D1, mediated drought response in apple plants (Malus domestica). MdRAD23D1 levels increased under drought stress, and its suppression resulted in decreased stress tolerance in apple plants. Through in vitro and in vivo assays, we demonstrated that MdRAD23D1 interacted with a proline‐rich protein MdPRP6, resulting in the degradation of MdPRP6 by the 26S proteasome. And MdRAD23D1 accelerated the degradation of MdPRP6 under drought stress. Suppression of MdPRP6 resulted in enhanced drought tolerance in apple plants, mainly because the free proline accumulation is changed. And the free proline is also involved in MdRAD23D1‐mediated drought response. Taken together, these findings demonstrated that MdRAD23D1 and MdPRP6 oppositely regulated drought response. MdRAD23D1 levels increased under drought, accelerating the degradation of MdPRP6. MdPRP6 negatively regulated drought response, probably by regulating proline accumulation. Thus, "MdRAD23D1‐MdPRP6" conferred drought stress tolerance in apple plants. [ABSTRACT FROM AUTHOR]

SUMMARY: Plant A/T‐rich protein and zinc‐binding protein (PLATZ) transcription factors play important roles in plant growth, development and abiotic stress responses. However, how PLATZ influences plant drought tolerance remains poorly understood. The present study showed that PLATZ4 increased drought tolerance in Arabidopsis thaliana by causing stomatal closure. Transcriptional profiling analysis revealed that PLATZ4 affected the expression of a set of genes involved in water and ion transport, antioxidant metabolism, small peptides and abscisic acid (ABA) signaling. Among these genes, the direct binding of PLATZ4 to the A/T‐rich sequences in the plasma membrane intrinsic protein 2;8 (PIP2;8) promoter was identified. PIP2;8 consistently reduced drought tolerance in Arabidopsis through inhibiting stomatal closure. PIP2;8 was localized in the plasma membrane, exhibited water channel activity in Xenopus laevis oocytes and acted epistatically to PLATZ4 in regulating the drought stress response in Arabidopsis. PLATZ4 increased ABA sensitivity through upregulating the expression of ABSCISIC ACID INSENSITIVE 3 (ABI3), ABI4 and ABI5. The transcripts of PLATZ4 were induced to high levels in vegetative seedlings under drought and ABA treatments within 6 and 3 h, respectively. Collectively, these findings reveal that PLATZ4 positively influences plant drought tolerance through regulating the expression of PIP2;8 and genes involved in ABA signaling. Significance Statement: PLATZs have been demonstrated to play important roles in plant growth, development and responses to environmental stimuli, but how they affect drought stress remain unknown. For these purposes, we reveal that PLATZ4 increases drought tolerance by regulating the expression of PIP2;8 and genes involved in ion transport, antioxidant metabolism, small peptides and abscisic acid signaling. We also reveal the aquaporin activity of PIP2;8 and its roles in regulating drought stress. These findings extend the current view about the regulatory mechanism of PLATZs and the function of PIP2;8. [ABSTRACT FROM AUTHOR]

Poly (acrylic) acid coated Mn3O4 nanoparticles (PAA@Mn3O4 nanoparticles (PMO, 11.02 nm, −28.93 mV)) are synthesized to investigate whether they can help to improve maize drought tolerance and the relevant mechanisms behind this. In planta experimental results show that under drought (15% PEG 6000, polyethylene glycol, mimicking drought stress, 96 h), compared with the control plants, 500 mg L−1 PMO (root application, 96 h) improves maize drought tolerance, showing an increase of root length (21.6%), shoot length (21.2%), fresh weight (7.8%) and total protein (67.2%) content. In addition, PMO significantly decreases the malondialdehyde (MDA) content by 74.7% in maize under drought, compared with the control group. Further, PMO treated maize root apex shows significantly increased mitotic index (MI, 35.5%), and decreased hydrogen peroxide (40.9%). Compared with the control under drought (15% PEG, 96 h), thr root apex of maize plants treated with PMO (500 mg L−1, root application, 96 h) have significantly lower level of H2O2. Overall, the results show that PMO can alleviate drought‐inhibited cell mitosis activities via maintaining ROS (reactive oxygen species) homeostasis. In this study, it is not only shown that PMO can be a good nano‐regulator candidate to improve maize drought tolerance, but also that PMO has potential to modulate plant cell mitosis activities. [ABSTRACT FROM AUTHOR]

Ongoing climatic changes have altered growing conditions for plants by limiting water availability and inducing unprecedented temperature increases, eliciting plant functional responses that compromise floral trait expression, reduce pollen production and promote early self‐pollination. In a controlled greenhouse study, plants of Collinsia heterophylla, an annual mixed‐mated hermaphrodite, were grown under temperature and water stresses. Floral trait responses and related effects on plant reproductive success were recorded. Plants grown under temperature and water stresses were shorter and had fewer leaves at flowering than control plants. Temperature‐stressed plants flowered earlier and had smaller flowers that produced fewer per capita pollen grains than control and water‐stressed plants. While lifetime flower production in plants experiencing temperature stress alone or water stress alone was similar to control plants, those receiving combined temperature and water stresses had significantly lower lifetime flower production. Abiotic stress did not affect investment in female traits such as ovule number per flower, but impacted male traits seen as fewer pollen grains per flower. In plants experiencing abiotic stress, an increase in autonomous self‐pollination was facilitated through a compromise in herkogamy, a sexual interference mechanism that promotes cross‐pollination. Spatial separation between stigma and anther, a measure of herkogamy was zero or negative in stressed plants. Thus, abiotic stress responses in plants did not compromise plant reproductive success as autonomous selfing was augmented. In nature, such responses will likely reduce available nutrition for pollinators through decreased flower and pollen production. [ABSTRACT FROM AUTHOR]

Drought stress is a major environmental factor that limits the growth, development, and yield of rice (Oryza sativa L.). Histone deacetylases (HDACs) are involved in the regulation of drought stress responses. HDA704 is an RPD3/HDA1 class HDAC that mediates the deacetylation of H4K8 (lysine 8 of histone H4) for drought tolerance in rice. In this study, we show that plants overexpressing HDA704 (HDA704‐OE) are resistant to drought stress and sensitive to abscisic acid (ABA), whereas HDA704 knockout mutant (hda704) plants displayed decreased drought tolerance and ABA sensitivity. Transcriptome analysis revealed that HDA704 regulates the expression of ABA‐related genes in response to drought stress. Moreover, HDA704 was recruited by a drought‐resistant transcription factor, WAX SYNTHESIS REGULATORY 2 (OsWR2), and co‐regulated the expression of the ABA biosynthesis genes NINE‐CIS‐EPOXYCAROTENOID DIOXYGENASE 3 (NCED3), NCED4, and NCED5 under drought stress. HDA704 also repressed the expression of ABA‐INSENSITIVE 5 (OsABI5) and DWARF AND SMALL SEED 1 (OsDSS1) by regulating H4K8ac levels in the promoter regions in response to polyethylene glycol 6000 treatment. In agreement, the loss of OsABI5 function increased resistance to dehydration stress in rice. Our results demonstrate that HDA704 is a positive regulator of the drought stress response and offers avenues for improving drought resistance in rice. [ABSTRACT FROM AUTHOR]

Summary: N6‐methyladenosine (m6A) is the most prevalent internal modification present in mRNAs, and is considered to participate in a range of developmental and biological processes. Drought response is highly regulated at the genomic, transcriptional and post‐transcriptional levels. However, the biological function and regulatory mechanism of m6A modification in the drought stress response is still poorly understood. We generated a transcriptome‐wide m6A map using drought‐resistant and drought‐sensitive varieties of cotton under different water deficient conditions to uncover patterns of m6A methylation in cotton response to drought stress. The results reveal that m6A represents a common modification and exhibit dramatic changes in distribution during drought stress. More 5'UTR m6A was deposited in the drought‐resistant variety and was associated with a positive effect on drought resistance by regulating mRNA abundance. Interestingly, we observed that increased m6A abundance was associated with increased mRNA abundance under drought, contributing to drought resistance, and vice versa. The demethylase GhALKBH10B was found to decrease m6A levels, facilitating the mRNA decay of ABA signal‐related genes (GhZEP, GhNCED4 and GhPP2CA) and Ca2+ signal‐related genes (GhECA1, GhCNGC4, GhANN1 and GhCML13), and mutation of GhALKBH10B enhanced drought resistance at seedling stage in cotton. Virus‐induced gene silencing (VIGS) of two Ca2+‐related genes, GhECA1 and GhCNGC4, reduced drought resistance with the decreased m6A enrichment on silenced genes in cotton. Collectively, we reveal a novel mechanism of post‐transcriptional modification involved in affecting drought response in cotton, by mediating m6A methylation on targeted transcripts in the ABA and Ca2+ signalling transduction pathways. [ABSTRACT FROM AUTHOR]

Date palm (Phoenix dactylifera L.) fruit is one of the ancient crops that have been cultivated for thousands of years in the arid regions of the Middle East and North Africa. Its nutritional and economic importance has extended the cultivation to other countries with suitable environmental conditions. Despite the large expansion in date palm cultivation and the associated improvement in its yield and quality over the last few decades, challenges remain in its cultivation and sustainability. Here, we review: (1) the current status of date palm cultivation, (2) the key environmental and soil‐related factors influencing its cultivation and productivity, and (3) the challenges under global change in addition to assessing the future potentials for improvements and sustainability. The global production of date palm has increased by 18% during the last ten years, reaching 8.53 million tons, on a total area of 1.11 million ha. Water scarcity and salinity stresses are the major constraints affecting date palm productivity, which is a serious issue in arid regions, where water resources are becoming depleted and soil is becoming increasingly salinized due to limited rainfall, high evapotranspiration, and incorrect irrigation. Although date palm can tolerate salinity up to 12 dS m−1, accumulation of salts in soil strongly reduces the yield. The main cultivation areas are dominated by soils of sandy texture with high pH and a low capacity for water and nutrient retention. Organic fertilizers increase water and nutrient retention. There is a lack of long‐term studies (e.g., ≥10 years) designed to monitor date palm cultivar responses to abiotic stresses as well as to nutrition and management practices. Future challenges facing date palm cultivation mainly include water shortages, extremely high temperatures, salinity, and soil degradation, as well as diseases and pests. The implementation of efficient management practices, including modern irrigation systems, selecting cultivars most suitable for the local environmental conditions, and increasing soil water and nutrient retention, help to sustain date palm cultivation and productivity. [ABSTRACT FROM AUTHOR]

Aim: Climate change regulates autumn leaf senescence date (LSD), exhibiting a strong phenological control of plant carbon uptake. Unlike the delaying effect of daily mean temperature (Tmean) on LSD, the impact of warming asymmetry in daytime and nighttime, as evidenced by variations of the diurnal temperature range (DTR), remains elusive. The objectives of this study were to investigate physiological and ecological impacts of DTR on LSD using long‐term in situ observations and to predict the future trends of LSD under warming. Location: Europe. Time period: 1950–2015. Major taxa studied: Plant phenology. Methods: We used partial correlation analysis, multiple linear regression and ridge regression to explore the impacts of DTR on LSD. To quantify the importance of potential drivers of LSD, we trained random forest models and applied the SHapley Additive exPlanations method to isolate the marginal contributions of each predictor on LSD. For LSD modelling and projection, we first evaluated two temperature‐driven LSD models [i.e., cooling‐degree‐day (CDD, without DTR effect) and day–night‐temperature CDD (DNCDD, with DTR effect)], then applied them to predict future LSDs. Results: We found that observational increases in Tmean and DTR had contrasting effects on LSD. Increased Tmean delayed the LSD, whereas larger DTR overall had an advancing effect. Considering the DTR effect, the Tmean sensitivity of LSD was 14% lower than presently estimated (2.4 vs. 2.8 days °C−1). Warming asymmetry‐related drought stress and plant functional traits (i.e., plant isohydricity and water‐use efficiency) potentially explained the advancing effect of DTR on LSD. We found that current projections of future LSD are overestimated because the DTR effect is discounted, suggesting the need for an adequate understanding of how plant phenology responds to warming asymmetry. Main conclusions: Our findings highlight the importance of DTR in controlling LSD variations with an advancing‐dominant effect and call for the improvement of phenology modelling incorporating the DTR effect. Given that DTR showed a globally narrowing trend over the last several decades, more efforts are needed to understand the potential ecological impacts of warming asymmetry and vegetation response to climate change. [ABSTRACT FROM AUTHOR]

SUMMARY: Drought is a major abiotic stress reducing maize (Zea mays) yield worldwide especially before and during silking. The mechanism underlying drought tolerance in maize and the roles of different organs have not been elucidated. Hence, we conducted field trials under pre‐silking drought conditions using two maize genotypes: FM985 (drought‐tolerant) and ZD958 (drought‐sensitive). The two genotypes did not differ in plant height, grain number, and yield under control conditions. However, the grain number per ear and the yield of FM985 were 38.1 and 35.1% higher and plants were 17.6% shorter than ZD958 under drought conditions. More 13C photosynthates were transported to the ear in FM985 than in ZD958, which increased floret fertility and grain number. The number of differentially expressed genes was much higher in stem than in other organs. Stem–ear interactions are key determinants of drought tolerance, in which expression of genes related to abscisic acid, lignin, and flavonoid biosynthesis and carbon metabolism in the stem was induced by drought, which inhibited stem elongation and promoted assimilate allocation to the ear in FM985. In comparison with ZD958, the activities of trehalose 6‐phosphate phosphatase and sucrose non‐fermentation‐associated kinase 1 were higher in the stem and lower in the kernel of FM985, which facilitated kernel formation. These results reveal that, beyond the ear response, stem elongation is involved in the whole process of drought tolerance before silking. Abscisic acid together with trehalose 6‐phosphate, lignin, and flavonoid suppresses stem elongation and allocates assimilates into the ear, providing a novel and systematic regulatory pathway for drought tolerance in maize. [ABSTRACT FROM AUTHOR]

SUMMARY: Drought stress is one of the major constraints of global crop production. Raffinose, a non‐reducing trisaccharide, has been considered to regulate positively the plant drought stress tolerance; however, evidence that augmenting raffinose production in leaves results in enhanced plant drought stress tolerance is lacking. The biochemical mechanism through which raffinose might act to mitigate plant drought stress remains unidentified. ZmRAFS encodes Zea mays RAFFINOSE SYNTHASE, a key enzyme that transfers galactose from the galactoside galactinol to sucrose for raffinose production. Overexpression of ZmRAFS in maize increased the RAFS protein and the raffinose content and decreased the water loss of leaves and enhanced plant drought stress tolerance. The biomass of the ZmRAFS overexpressing plants was similar to that of non‐transgenic control plants when grown under optimal conditions, but was significantly greater than that of non‐transgenic plants when grown under drought stress conditions. In contrast, the percentage of water loss of the detached leaves from two independent zmrafs mutant lines, incapable of synthesizing raffinose, was greater than that from null segregant controls and this phenomenon was partially rescued by supplementation of raffinose to detached zmrafs leaves. In addition, while there were differences in water loss among different maize lines, there was no difference in stomata density or aperture. Taken together, our work demonstrated that overexpression of the ZmRAFS gene in maize, in contrast to Arabidopsis, increased the raffinose content in leaves, assisted the leaf to retain water, and enhanced the plant drought stress tolerance without causing a detectable growth penalty. Significance Statement: Raffinose has been positively correlated with drought tolerance but its mechanism of action remains obscure. The amounts of raffinose increased in leaves of maize plants constitutively overexpressing its RAFFINOSE SYNTHASE gene, which then assisted the leaf to retain water, and enhanced the plant drought stress tolerance without a growth penalty. Raffinose exerts its protective effect independent of leaf stomata density, and aperture or the cell plasma membrane structure; presumably through its in vitro demonstrable physical, hygroscopic properties. [ABSTRACT FROM AUTHOR]

Summary: Arginine decarboxylase (ADC)‐mediated putrescine (Put) biosynthesis plays an important role in plant abiotic stress response. SNF1‐related protein kinases 2s (SnRK2s) and abscisic acid (ABA)‐response element (ABRE)‐binding factors (ABFs), are core components of the ABA signaling pathway involved in drought stress response. We previously reported that ADC of Poncirus trifoliata (PtrADC) functions in drought tolerance. However, whether and how SnRK2 and ABF regulate PtrADC to modulate putrescine accumulation under drought stress remains largely unclear.Herein, we employed a set of physiological, biochemical, and molecular approaches to reveal that a protein complex composed of PtrSnRK2.4 and PtrABF2 modulates putrescine biosynthesis and drought tolerance by directly regulating PtrADC.PtrABF2 was upregulated by dehydration in an ABA‐dependent manner. PtrABF2 activated PtrADC expression by directly and specifically binding to the ABRE core sequence within its promoter and positively regulated drought tolerance via modulating putrescine accumulation. PtrSnRK2.4 interacts with and phosphorylates PtrABF2 at Ser93. PtrSnRK2.4‐mediated PtrABF2 phosphorylation is essential for the transcriptional regulation of PtrADC. Besides, PtrSnRK2.4 was shown to play a positive role in drought tolerance by facilitating putrescine synthesis.Taken together, this study sheds new light on the regulatory module SnRK2.4‐ABF2‐ADC responsible for fine‐tuning putrescine accumulation under drought stress, which advances our understanding on transcriptional regulation of putrescine synthesis. [ABSTRACT FROM AUTHOR]

Changes in climate have intensified the drought in semi‐arid regions. A shift toward cultivation of low‐input crops, including high‐value medicinal and herbal plants seems a more sustainable alternative strategy. A 2‐year field study was conducted to investigate the influence of drought stress and chitosan on nutrient density and phenolic compounds of thyme. Treatments consisted of a factorial combination of three irrigation and three chitosan rates. Irrigation treatments consisted of keeping experimental plots at field capacity (no stress), irrigation when plots reached 50% of field capacity (mild stress), and irrigation when plots reached 25% of field capacity (severe stress). Chitosan rates were 0, 200, and 400 μL L−1, while K+, and to some degree Ca+2, accumulation increased by drought, N, P, and all micronutrients (Mn2+, Zn2+, Cu2+, and Fe2+) decreased steadily as drought stress intensified. Drought stress reduced N and P by 23%–19% and 35%–23%, respectively, over the 2 years. Application of chitosan enhanced the accumulation of macro and micronutrients. Drought stress resulted in alterations in phenolic composition. In mature plants, almost all phenolic compounds, except thymol, increased as drought stress intensified. Cinnamic acid and rosmarinic contents, as the two major identified compounds, increased by 31% and 45%, respectively, under severe drought. Similar to drought, chitosan elicitation was more effective in elevating phenolic compounds in mature plants. The response of thyme to chitosan was independent of soil moisture availability. The results indicated that application of 400 μL−1 chitosan improved nutrient density and dry matter while significantly saved irrigation water. Core Ideas: In semiarid environments, the cultivation of medicinal crops improves the sustainability of farming.Drought stress increases the concentration of economic secondary metabolites in thyme.Foliar application of chitosan improves macro and micronutrient density in thyme.Foliar application of chitosan elevates phenolic compounds in thyme. [ABSTRACT FROM AUTHOR]

Temperate Pooideae are a large clade of economically important grasses distributed in some of the Earth's coldest and driest terrestrial environments. Previous studies have inferred that Pooideae diversified from their tropical ancestors in a cold montane habitat, suggesting that above‐freezing cold (chilling) tolerance evolved early in the subfamily. By contrast, drought tolerance is hypothesized to have evolved multiple times independently in response to global aridification that occurred after the split of Pooideae tribes. To independently test predictions of the chilling‐before‐drought hypothesis in Pooideae, we assessed conservation of whole plant and gene expression traits in response to chilling vs. drought. We demonstrated that both trait responses are more similar across tribes in cold as compared to drought, suggesting that chilling responses evolved before, and drought responses after, tribe diversification. Moreover, we found significantly more overlap between drought and chilling responsive genes within a species than between drought responsive genes across species, providing evidence that chilling tolerance genes acted as precursors for the novel acquisition of increased drought tolerance multiple times independently, partially through the cooption of chilling responsive genes. [ABSTRACT FROM AUTHOR]

BACKGROUND: Drought stress (DS) induced by post-silking have a major impact on the yield and quality of maize. In this study, the effects of different degrees of DS after pollination on grain filling, starch and protein metabolism, and functional properties were investigated using two waxy maize cultivars as materials. The levels of DS that were investigated were 'mild water stress' (WS1), 'moderate water stressed' (WS2), and 'severe waterstressed' (WS3). RESULTS: Drought stress decreased grain fresh weight, dry weight, and moisture content in both cultivars during grain filling, and reduced kernel number, kernel weight, and grain yield at maturity. The effect on grain development and yield formation gradually increased with drought aggravation. The water stress (WS) treatment downregulated the enzymatic activities related to starch biosynthesis during grain-filling process, accompanied by a decrease in soluble sugar and starch deposition. The WS treatment increased the enzymatic activities involved in protein synthesis during grain-filling process, thereby increasing the protein content of grains. On average, WS2 and WS3 treatments reduced the pasting viscosities and increased the gelatinization temperatures of grains, with WS3 having the greatest effect. However, the changes of setback viscosity, gelatinization enthalpy, retrogradation enthalpy, and retrogradation percentage under WS treatment were inconsistent in both cultivars. Pearson correlation analysis showed that starch content was negatively correlated with gelatinization temperatures and positively correlated with pasting viscosities in both cultivars. However, grain pasting and gelatinization properties have opposite correlations with protein content and starch content. CONCLUSIONS: These findings suggest that post-silking DS regulated the grain-filling process and starch and protein biosynthesis, which influenced grain yield and quality. [ABSTRACT FROM AUTHOR]

Uganda lies within the drier end of the natural distribution range of Coffea canephora and contains unexplored genetic material that could be drought‐adapted and useful for developing climate‐resilient varieties. Using water treatment: (i) ample and (ii) restricted‐water, the response of 148 genotypes were studied comprising wild, feral and cultivated C. canephora. Biomass allocation, standing leaf area and leaf area growth data were collected. Linear mixed effect models and PCA were used to the analyze effect of water treatment on genotypes from different: (i) cultivation status, (ii) genetic groups and (iii) locations. We also assessed the relationship between drought tolerance for relative growth rate in leaf area (RGRA), total number of leaves (TNL), total leaf area (TLA) and total leaf dry weight (TLDW) of genotypes at final harvest. Restricted‐water reduced RGRA across genetic groups (3.2–32.5%) and locations (7.1–36.7%) but not cultivation status. For TNL, TLA and TLDW, genotypes that performed well in ample‐water performed worse under restricted‐water, indicating growth‐tolerance trade‐off. Drought tolerance in RGRA and TNL were negatively correlated with wetness index suggesting some degree of adaptation to local climate. Findings indicate a growth‐tolerance trade‐off within this tropical tree species and drought tolerance of Uganda's C. canephora is somewhat associated with local climate. [ABSTRACT FROM AUTHOR]

Riparian trees are critically important for maintaining the ecological function of freshwater ecosystems. Globally, anthropogenic changes to water regimes are impacting the health and distribution of riparian trees. Understanding the physiological constraints on the distribution of riparian tree species in relation to the water regime is essential for informed water resource management that seeks to limit impacts on riparian trees. To fill an identified knowledge gap for the Fitzroy River, a significant river in the wet–dry tropics of north‐western Australia, we used a trait‐based approach to characterise nine common riparian tree species in relation to their distribution along a hydrological gradient. We assessed key functional traits related to drought and flood flows. Leaf mass per unit area (LMA), leaf dry matter content (LDMC), foliar carbon content (% C) and the ratio of carbon to nitrogen (C:N) are broadly related to plant productivity and durability and may reflect resistance to fluvial stress. Traits related to water availability were stem specific density (SSD), mean xylem vessel diameter and xylem vessel density, as well as foliar δ13C which is related to water use efficiency, and leaf osmotic potential at full hydration (π100) as a measure of drought tolerance. We found that π100, δ13C and SSD values reflected species hydrological habitat preferences, with higher δ13C values and lower π100 for species distributed in the drier floodplain habitats, compared with species constrained to the riverbank. Low SSD values for species close to the riverbank may be indicative of aerenchyma tissue in response to flooding. Differences in leaf trait values were primarily attributed to differences between evergreen Myrtaceous and deciduous non‐Myrtaceous species, rather than hydrological habitat preferences. LMA was greatest for the Myrtaceous study species, with deciduous non‐Myrtaceous species associated with wetter habitats having the lowest values. The physiology of riparian trees in northern Australia is not well described for the majority of species. Our study provides insight into plant functional strategies in response to both flooding and drought and is a critical step in understanding plant responses to future water‐take scenarios to support evidence‐based decision making. [ABSTRACT FROM AUTHOR]

SUMMARY: The effects of drought on photosynthesis have been extensively studied, whereas those on thylakoid organization are limited. We observed a significant decline in gas exchange parameters of pea (Pisum sativum) leaves under progressive drought stress. Chl a fluorescence kinetics revealed the reduction of photochemical efficiency of photosystem (PS)II and PSI. The non‐photochemical quenching (NPQ) and the levels of PSII subunit PSBS increased. Furthermore, the light‐harvesting complexes (LHCs) and some of the PSI and PSII core proteins were disassembled in drought conditions, whereas these complexes were reassociated during recovery. By contrast, the abundance of supercomplexes of PSII‐LHCII and PSII dimer were reduced, whereas LHCII monomers increased following the change in the macro‐organization of thylakoids. The stacks of thylakoids were loosely arranged in drought‐affected plants, which could be attributed to changes in the supercomplexes of thylakoids. Severe drought stress caused a reduction of both LHCI and LHCII and a few reaction center proteins of PSI and PSII, indicating significant disorganization of the photosynthetic machinery. After 7 days of rewatering, plants recovered well, with restored chloroplast thylakoid structure and photosynthetic efficiency. The correlation of structural changes with leaf reactive oxygen species levels indicated that these changes were associated with the production of reactive oxygen species. Significance Statement: Drought affects the photosynthetic apparatus and organization of thylakoid proteins, which are relatively reversible by rewatering. The present study shows that the drought conditions equally damaged both photosystems. [ABSTRACT FROM AUTHOR]

SUMMARY: Lateral organ boundaries domain (LBD) proteins are plant‐specific transcription factors. Class‐I LBD genes have been widely demonstrated to play pivotal roles in organ development; however, knowledge on class‐II genes remains limited. Here, we report that ZmLBD5, a class‐II LBD gene, is involved in the regulation of maize (Zea mays) growth and the drought response by affecting gibberellin (GA) and abscisic acid (ABA) synthesis. ZmLBD5 is mainly involved in regulation of the TPS‐KS‐GA2ox gene module, which is comprised of key enzyme‐encoding genes involved in GA and ABA biosynthesis. ABA insufficiency increases stomatal density and aperture in overexpression plants and causes a drought‐sensitive phenotype by promoting water transpiration. Increased GA1 levels promotes seedling growth in overexpression plants. Accordingly, CRISPR/Cas9 knockout lbd5 seedlings are dwarf but drought‐tolerant. Moreover, lbd5 has a higher grain yield under drought stress conditions and shows no penalty in well‐watered conditions compared to the wild type. On the whole, ZmLBD5 is a negative regulator of maize drought tolerance, and it is a potentially useful target for drought resistance breeding. Significance Statement: Maize (Zea mays) ZmLBD5 is mainly associated with abscisic acid (ABA) and gibberellin (GA) synthesis by regulating the TPS‐KS‐GA2ox gene module, which is comprised of key enzyme‐encoding genes involved in GA and ABA biosynthesis. ZmLBD5 negatively regulates drought tolerance by repressing ABA synthesis and promoting stomatal development and opening; however, lbd5 mutants have higher grain yield under drought stress conditions and show no penalty in well‐watered conditions compared to the wild type. [ABSTRACT FROM AUTHOR]

Summary: The INDETERMINATE DOMAIN (IDD) transcription factors mediate various aspects of plant growth and development. We previously reported that an Arabidopsis IDD subfamily regulates spatial auxin accumulation, and thus organ morphogenesis and gravitropic responses. However, its functions in stress responses are not well defined.Here, we use a combination of physiological, biochemical, molecular, and genetic approaches to provide evidence that the IDD14 cooperates with basic leucine zipper‐type binding factors/ABA‐responsive element (ABRE)‐binding proteins (ABRE‐binding factors (ABFs)/AREBs) in ABA‐mediated drought tolerance.idd14‐1D, a gain‐of‐function mutant of IDD14, exhibits decreased leaf water loss and improved drought tolerance, whereas inactivation of IDD14 in idd14‐1 results in increased transpiration and reduced drought tolerance. Altered IDD14 expression affects ABA sensitivity and ABA‐mediated stomatal closure. IDD14 can physically interact with ABF1–4 and subsequently promote their transcriptional activities. Moreover, ectopic expression and mutation of ABFs could, respectively, suppress and enhance plant sensitivity to drought stress in the idd14‐1 mutant.Our results demonstrate that IDD14 forms a functional complex with ABFs and positively regulates drought‐stress responses, thus revealing a previously unidentified role of IDD14 in ABA signaling and drought responses. [ABSTRACT FROM AUTHOR]

Overexpression of Arabidopsis dehydration response element binding 1a (DREB1a) is a well‐known approach for developing salinity, cold and/or drought stress tolerance. However, understanding of the genetic mechanisms associated with DREB1a expression in rice is generally limited. In this study, DREB1a‐associated early responses were investigated in a transgenic rice line harboring cold‐inducible DREB1a at a gene stacked locus. Although the function of other genes in the stacked locus was not relevant to stress tolerance, this study demonstrates DREB1a can be co‐localized with other genes for multigenic trait enhancement. As expected, the transgenic lines displayed improved tolerance to salinity stress and water withholding as compared with non‐transgenic controls. RNA sequencing and transcriptome analysis showed upregulation of complex transcriptional networks and metabolic reprogramming as DREB1a expression led to the upregulation of multiple transcription factor gene families, suppression of photosynthesis, and induction of secondary metabolism. In addition to the detection of previously described mechanisms such as production of protective molecules, potentially novel pathways were also revealed. These include jasmonate, auxin, and ethylene signaling, induction of JAZ and WRKY regulons, trehalose synthesis, and polyamine catabolism. These genes regulate various stress responses and ensure timely attenuation of the stress signal. Furthermore, genes associated with heat stress response were downregulated in DREB1a expressing lines, suggesting antagonism between heat and dehydration stress response pathways. In summary, through a complex transcriptional network, multiple stress signaling pathways are induced by DREB1a that presumably lead to early perception and prompt response toward stress tolerance as well as attenuation of the stress signal to prevent deleterious effects of the runoff response. [ABSTRACT FROM AUTHOR]

The return of vegetation to mined lands often requires broadcast seeding of diverse native seed mixes. However, seeds are highly adapted to germination windows with specific hydrothermal thresholds that maximize the likelihood of seedling survival, and post‐mining landscapes typically offer markedly different hydrothermal conditions than pre‐disturbance ecosystems. According to niche theory, generalist species should exhibit broader hydrothermal performance niches than specialist taxa, which may influence the success of recruitment from seeds in post‐mining ecological restoration. To test this assumption, the impact of hydrothermal stress (incubation temperature (10–30°C) and osmotic potential (−0.8 to 0 MPa)) on the time to 50% germination (t50) and maximum germination (Gmax) was compared between two narrow‐range species of conservation concern (Acacia woodmaniorum and A. karina) restricted to mining‐impacted Banded Ironstone Formations (BIF) and three broadly distributed congenerics (A. assimilis, A. exocarpoides, and A. ramulosa). The hydrothermal germination niches of the study species were broadly congruent with hydrothermal conditions of their habitats. The two range‐restricted taxa were more tolerant of hydrothermal stress compared to the three widely distributed taxa, suggesting that tolerance of greater hydrothermal stress by both range‐restricted Acacia species is likely to be adaptive to establishment in uncontested niche space. Complex interactions between thermal and water stress suggest these environmental gradients may shape the germination niche as well as patterns of plant diversity in BIF ecosystems. This study highlights the importance of quantifying interactions between niche dimensions and their implications for species performance, which will aid future restoration efforts for micro‐endemic species impacted by mining. [ABSTRACT FROM AUTHOR]

Maize is acutely vulnerable to water deficit. Due to the slow progress in conventional breeding, more beneficial genes should be transformed into maize for improvement of drought tolerance. In the present study, the vacuolar H+-pyrophosphatase (H+-PPase) gene (AnVP1) from Ammopiptanthus nanus was transformed into maize by Agrobacterium-mediated calli transformation. After identification of integration and ectopic expression of the AnVP1 gene by PCR amplification, DNA resequencing, reverse transcription PCR, real-time quantitative PCR, Western blotting and measurement of H+-PPase content, the transgenic lines were evaluated for their drought tolerance in greenhouse and field. The results of greenhouse phenotyping showed that the expression of AnVP1 decreased the negative effects of drought stress on transgenic maize with the improved performance, higher germination ratio, relative water content, biomass and more robust root system, slightly blasted leaves, lower electrolyte leakage and malondialdehyde content. The results of yield phenotyping showed that kernel yield of L1, L4 and L10 lines was significantly higher than WT under water deficit conditions. In conclusion, ectopic expression of the AnVP1 gene significantly enhanced drought tolerance of the transgenic maize, which is hopefully used for commercialized release after further safety assessment, because the expression of some endogenous genes was affected slightly. [ABSTRACT FROM AUTHOR]

In cultivating guar [Cyamopsis tetragonoloba (L.) Taub], a drought-tolerant legume, producers anticipate soil N credits through biological N fixation (BNF), but it has been speculated that root nodulation is poor under dry conditions and little is known about how nodules recover from drought stress. To provide better insight, two greenhouse studies were conducted to investigate static (25%, 50%, 75% and 100% ET replacement in two soils) and dynamic (50%, 75% and 100%, plus 50% and 75% relieved to 100% at 20 and 30 days after planting) water regimes on guar over 50 days. Water stress generally had the greatest negative impact on nodule weight, followed by aboveground biomass, reproductive nodes, height and then nodule number. Parameter responses were either linear or quadratic with ET replacement and response slopes differed between soils for nodule weight and biomass. The relatively minor effect on nodule number indicated the basic machinery for BNF (nodules) remained largely intact until water stress was extreme. This was likely a key factor that enabled strong and rapid recovery of nodule growth following relief of water stress. Biomass recovery was likewise robust, with production equal to the stress-free control, regardless of the intensity and duration of the stress. These results show that nodule growth in guar is highly sensitive to water stress, but the plant is resilient in maintaining nodules under water stress and recovering nodule growth upon moisture restoration. [ABSTRACT FROM AUTHOR]

Drought is the main limiting factor for plant growth in karst areas with a fragile ecological environment. Cinnamomum migao H.W. Li is an endemic medicinal woody plant present in the karst areas of southwestern China, and it is endangered due to poor drought tolerance. Arbuscular mycorrhizal fungi (AMF) are known to enhance the drought tolerance of plants. However, few studies have examined the contribution of AMF in improving the drought tolerance of C. migao seedlings. Therefore, we conducted a series of experiments to determine whether a single inoculation and coinoculation of AMF (Claroideoglomus lamellosum and Claroideoglomus etunicatum) enhanced the drought tolerance of C. migao. Furthermore, we compared the effects of single inoculation and coinoculation with different inoculum sizes (20, 40, 60, and 100 g; four replicates per treatment) on mycorrhizal colonization rate, plant growth, photosynthetic parameters, antioxidant enzyme activity, and malondialdehyde (MDA) and osmoregulatory substance contents. The results showed that compared with nonmycorrhizal plants, AMF colonization significantly improved plant growing status; net photosynthetic rate; superoxide dismutase, catalase, and peroxidase activities; and soluble sugar, soluble protein, and proline contents. Furthermore, AMF colonization increased relative water content and reduced MDA content in cells. These combined cumulative effects of AMF symbiosis ultimately enhanced the drought tolerance of seedlings and were closely related to the inoculum size. With an increase in inoculum size, the growth rate and drought tolerance of plants first increased and then decreased. The damage caused by drought stress could be reduced by inoculating 40–60 g of AMF, and the effect of coinoculation was significantly better than that of single inoculation at 60 g of AMF, while the effect was opposite at 40 g of AMF. Additionally, the interaction between AMF and inoculum sizes had a significant effect on drought tolerance. In conclusion, the inoculation of the AMF (Cl. lamellosum and Cl. etunicatum) improved photosynthesis, activated antioxidant enzymes, regulated cell osmotic state, and enhanced the drought tolerance of C. migao, enabling its growth in fragile ecological environments. [ABSTRACT FROM AUTHOR]

SUMMARY: The phytohormone abscisic acid (ABA) regulates ion channel activity and stomatal movement in response to drought stress. Cellular ABA levels change depending on cellular and environmental conditions via modulation of its biosynthesis, catabolism and transport. Although factors involved in ABA biosynthesis and degradation have been studied extensively, how ABA transporters are modulated to fine‐tune ABA levels, especially under drought stress, remains elusive. Here, we show that Arabidopsis thaliana SORTING NEXIN 2 (SNX2) proteins play a critical role in endosomal trafficking of the ABA exporter ATP BINDING CASETTE G25 (ABCG25) via direct interaction at endosomes, leading to its degradation in the vacuole. In agreement, snx2a and snx2b mutant plants showed enhanced recycling of GFP‐ABCG25 from early endosomes to the plasma membrane and higher accumulation of GFP‐ABCG25. Phenotypically, snx2a and snx2b plants were highly sensitive to exogenous ABA and displayed enhanced ABA‐mediated inhibition of inward K+ currents and ABA‐mediated activation of slow anion currents in guard cells, resulting in an increased tolerance to drought stress. Based on these results, we propose that SNX2 proteins play a crucial role in stomatal movement and tolerance to drought stress by modulating the endosomal trafficking of ABCG25 and thus cellular ABA levels. Significance Statement: Increasing evidence supports a role for sorting nexins (SNXs) in intracellular trafficking of membrane proteins; however, the role of SNX2 proteins in endomembrane protein trafficking remains elusive, and it is not clear whether and how they might function in response to abiotic stress. Here, we show that Arabidopsis SNX2a and SNX2b play a crucial role in stomatal movement and tolerance to drought stress via direct interaction with the abscisic acid exporter ABCG25 and modulation of its endosomal trafficking. [ABSTRACT FROM AUTHOR]

Drought stress seriously challenges wheat production and productivity. Grain biomass (GB) and related traits were assessed under drought stress and non‐stress for 285 and 185 durum wheat genotypes, respectively, in field and climate chamber experiments to identify quantitative trait loci (QTL). Significant correlations between traits estimated in field and climate chamber trials were observed (p <.001). Genotyping with the wheat 90 K iSelect single nucleotide polymorphism (SNP) array revealed 11,919 polymorphic SNP markers distributed across the durum wheat genome. The FarmCPU (Fixed and random model Circulating Probability Unification) method was used for genome‐wide association studies (GWAS). A total of 191 significant (−log10p ≥ 4) marker‐trait associations (MTAs) were detected at a linkage disequilibrium (LD, r2 ≥.2) at 4.78 Mb and were clustered into 70 QTLs. A total of 69 (36%) of the MTAs passed a false discovery rate (FDR) of 5%. The numbers of QTLs detected were 21, 31, 9 and 9 under field drought stress (FDS), field non‐stress (FNS), climate chamber drought stress (CCDS) and climate chamber non‐stress (CCNS) conditions, respectively. About 43% and 57% of the QTLs were located on the A and B genomes, respectively. Some of the detected QTLs were in agreement with previously reported QTLs, while others are novel ones for the traits investigated. QTLs on 1A between 495694477and ‐501944537bp, on 3B between 416256124 and 430507900 bp, on 3B between 745357158 and 759608934 bp, on 4B between 593416763 and 605142497 bp and on 4B between 658785890 and 670511624 bp were selected for validation and may be used to increase grain yield under drought stress in marker‐assisted selection (MAS) schemes. Key message: Genome‐wide association studies (GWAS) enabled detecting novel quantitative trait loci (QTLs) and identifying single nucleotide polymorphism (SNP) markers associated with grain biomass and correlated traits for drought stress tolerance in durum wheat based on a combination of climate chamber and multiyear and multilocation field experiments. [ABSTRACT FROM AUTHOR]

Recent changes in climate have reduced crop productivity throughout much of the world. Drought and heat stress, particularly in arid and semi‐arid regions, have seriously affected barley production.This study explored the separate and interactive effects of silicon (Si) and hydrogen sulphide (H2S) on plant growth and mitigation of the adverse effects of heat stress (DS) and drought stress (HS) in a barley pot experiment.The impacts of simultaneous DS + HS were more severe than individual stresses due to increased ROS production, malondialdehyde (MDA) content and higher electrolyte leakage (EL), thereby leading to reduced water, protein and photosynthetic pigment content. Exogenously applied Si and H2S alleviated the DS‐, HS‐ and DS + HS‐induced effects on barley by reducing ROS production, MDA and EL. A single application of H2S or Si + H2S increased plant biomass under all stress conditions, which can be ascribed to higher Si accumulation in barley shoots. A single application of Si or H2S significantly increased plant biomass. However, Si + H2S was the most effective treatment for metabolite accumulation and elevating activity of antioxidant enzymes to prevent toxicity from oxidative stress. This treatment also modulated osmolyte content, enhanced antioxidant activity and regulated the stress signalling‐related endogenous hormones, abscisic acid (ABA) and indole acetic acid (IAA).Exogenous treatments regulated endogenous H2S and Si and resulted in higher tolerance to individual and combined drought and heat stress in barley. [ABSTRACT FROM AUTHOR]

Leaves balance CO2 and radiative absorption while maintaining water transport to maximise photosynthesis. Related species with contrasting leaf anatomy can provide insights into inherent and stress‐induced links between structure and function for commonly measured leaf traits for important crops. We used two walnut species with contrasting mesophyll anatomy to evaluate these integrated exchange processes under non‐stressed and drought conditions using a combination of light microscopy, X‐ray microCT, gas exchange, hydraulic conductance, and chlorophyll distribution profiles through leaves. Juglans regia had thicker palisade mesophyll, higher fluorescence in the palisade, and greater low‐mesophyll porosity that were associated with greater gas‐phase diffusion (gIAS), stomatal and mesophyll (gm) conductances and carboxylation capacity. More and highly‐packed mesophyll cells and bundle sheath extensions (BSEs) in Juglans microcarpa led to higher fluorescence in the spongy and in proximity to the BSEs. Both species exhibited drought‐induced reductions in mesophyll cell volume, yet the associated increases in porosity and gIAS were obscured by declines in biochemical activity that decreased gm. Inherent differences in leaf anatomy between the species were linked to differences in gas exchange, light absorption and photosynthetic capacity, and drought‐induced changes in leaf structure impacted performance via imposing species‐specific limitations to light absorption, gas exchange and hydraulics. Summary Statement: Species‐specific differences in leaf anatomy between Juglans regia and Juglans microcarpa were linked to differences in CO2 diffusion, light absorption, water transport and carboxylation capacity. Drought‐induced changes in leaf structure impacted performance via CO2, water and light absorption. [ABSTRACT FROM AUTHOR]

Wheatgrass and barley grass are freshly sprouted leaves of wheat and barley seeds and are rich sources of phytochemicals. This study was conducted to investigate the effects of drought stress on the biochemical compounds and antioxidant activities of barley grass and wheatgrass extracts. The grass was cultivated in an organic soil growing medium with different levels of drought stress (a control with 100% water holding capacity (WHC), mild drought stress with 75% WHC, moderate drought stress with 50% WHC, and severe drought stress with 25% WHC) in a growth chamber by controlling temperature (20/15 °C, day/night), light (12/12 h, light/dark; intensity 150 μmol m−2 s−1 with quantum dot light‐emitting diodes), and relative humidity (60%) for 7 days. The drought stress showed increased levels of biochemical compounds, especially phenolics, flavonoids, and vitamin C, in both barley grass and wheatgrass extracts. The wheatgrass extracts showed 1.38–1.67 times higher phenolics, flavonoids, and vitamin C contents than the barley grass extracts did. The antioxidant (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid), 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging activity, and nitrite‐scavenging activity) and antioxidant enzymes (guaiacol peroxidase, catalase, and glutathione reductase) were the highest under severe drought stress in both barley grass and wheatgrass extracts; and the wheatgrass extracts showed 1.20–5.70 times higher antioxidant enzyme activities than the barley grass extracts did. Proper drought‐stress treatment of barley grass and wheatgrass may be a convenient and efficient method to increase biochemical compounds and antioxidants in our diet to exploit the related health benefits. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]