The impact of multifactorial stress combination on plants, crops, and ecosystems: how should we prepare for what comes next?

Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?

Climate change is altering our environment, subjecting multiple agroecosystems worldwide to an increased frequency and intensity of abiotic stress conditions such as heat, drought, flooding, salinity, cold and/or their potential combinations. These stresses impact plant growth, yield and survival, causing losses of billions of dollars to agricultural productivity, and in extreme cases they lead to famine, migration and even wars. As the rate of change in our environment has dramatically accelerated in recent years, more research is urgently needed to discover and develop new ways and tools to increase the resilience of crops to different stress conditions. In this theme issue, new studies addressing the molecular, metabolic, and physiological responses of crops and other plants to abiotic stress challenges are discussed, as well as the potential to exploit these mechanisms in biotechnological applications aimed at preserving and/or increasing crop yield under our changing climate conditions.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'

Using supervised machine-learning approaches to understand abiotic stress tolerance and design resilient crops

Abiotic stresses such as drought, heat, cold, salinity and flooding significantly impact plant growth, development and productivity. As the planet has warmed, these abiotic stresses have increased in frequency and intensity, affecting the global food supply and making it imperative to develop stress-resilient crops. In the past 20 years, the development of omics technologies has contributed to the growth of datasets for plants grown under a wide range of abiotic environments. Integration of these rapidly growing data using machine-learning (ML) approaches can complement existing breeding efforts by providing insights into the mechanisms underlying plant responses to stressful conditions, which can be used to guide the design of resilient crops. In this review, we introduce ML approaches and provide examples of how researchers use these approaches to predict molecular activities, gene functions and genotype responses under stressful conditions. Finally, we consider the potential and challenges of using such approaches to enable the design of crops that are better suited to a changing environment.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.

Needs and opportunities to future-proof crops and the use of crop systems to mitigate atmospheric change

Predicted changes in atmospheric composition and climate affecting crop productivity are reviewed. These include changes in both average conditions and extreme events, with respect to temperature, drought, flooding and surface ozone, coupled with rising atmospheric [CO2]. Impacts on, and means to adapt, crops to these changes are reviewed and outlined. Particular emphasis is given to (i) the results from open air field manipulations of surface atmosphere, temperature and soil water to understand impacts and adaptation and (ii) demonstrated genetic manipulations of photosynthesis and water use that could support future food supply under current and future conditions. Finally, attention is given to means by which crop systems could serve as CO2 collectors and carbon storage systems. Here, apparent opportunities are outlined for (i) manipulations of crops to enhance carbon storage and (ii) use of high-productivity sustainable perennial C4 grasses coupled with carbon capture and storage.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.

Genomics-assisted breeding for designing salinity-smart future crops

Climate change induces many abiotic stresses, including soil salinity, significantly challenging global agriculture. Salinity stress tolerance (SST) is a complex trait, both physiologically and genetically, and is conferred at various levels of plant functional organization. As both the sustainability and profitability of agricultural production systems are critically dependent on SST, plant breeders are trying to design and develop salinity-smart crop plants capable of thriving under high salinity conditions. The accessibility of extreme-quality reference genomes for cultivated crops, naturally salinity-smart plants, and crop wild relatives has fast-tracked the discovery of key genes and quantitative trait loci (QTLs), marker development, genotyping assays and molecular breeding products with improved SST. Employing fast-forward breeding tools, namely genomic selection (GS), haplotype-based breeding (HBB), artificial intelligence (AI) and high-throughput phenotyping (HTP), has shown influence not only for fast-tracking genetic gains but also for reducing the time and cost of developing commercial cultivars with enhanced SST and yield stability. This review discusses the advancement and prospects of various genomics-assisted breeding (GAB) tools, including genome sequencing, QTL mapping, GWAS, GS, HBB, pan-genomics, single-cell/tissue genomics and phenotyping, epigenomics and transgenomics, to exploit the genetic landscape for improving SST. Additionally, we explore the integration of HTP and AI, which demonstrates how these innovative approaches can optimize breeding efficiency and guide large-scale breeding efforts for designing salinity-smart crops to ensure sustainable agriculture and global food security. The collective adoption of these tools suggests bridging the gap between research and field application to deliver stress-smart varieties designed for saline-affected regions worldwide.

Elevated Growth Temperature Modifies Drought and Shade Responses of Fagus sylvatica Seedlings by Altering Growth, Gas Exchange, Water Relations, and Xylem Function

Climate change is increasing global temperatures and imposing new constraints on tree regeneration, especially in late-successional species exposed to simultaneous drought and low-light conditions. To disentangle the effects of warming from those of atmospheric drought, we conducted a multifactorial growth chamber experiment on Fagus sylvatica seedlings, manipulating temperature (25 °C and +7.5 °C above optimum), soil moisture (well-watered vs. water-stressed), and light intensity (high vs. low), while maintaining constant vapor pressure deficit (VPD). We assessed growth, biomass allocation, leaf gas exchange, water relations, and xylem hydraulic traits. Warming significantly reduced total biomass, leaf area, and water-use efficiency, while increasing transpiration and residual conductance, especially under high light. Under combined warming and drought, seedlings exhibited impaired osmotic adjustment, reduced leaf safety margins, and diminished hydraulic performance. Unexpectedly, warming under shade promoted a resource-acquisitive growth strategy through the production of low-cost leaves. These results demonstrate that elevated temperature, even in the absence of increased VPD, can compromise drought tolerance in beech seedlings and shift their ecological strategies depending on light availability. The findings underscore the need to consider multiple, interacting stressors when evaluating tree regeneration under future climate conditions.

Differential transpiration occurs in soybean under a wide range of water deficit and heat stress combination conditions

Differential transpiration is a newly discovered acclimation strategy of annual plants that mitigates the negative impacts of combined water deficit (WD) and heat stress (HS) on plant reproduction. Under conditions of WD + HS, transpiration of vegetative tissues is suppressed in plants such as soybean and tomato, while transpiration of reproductive tissues is not (termed 'Differential Transpiration'; DT). This newly identified acclimation process enables the cooling of reproductive organs under conditions of WD + HS, limiting HS-induced damage to plant reproduction. However, the thresholds at which DT remains active and effectively cools reproductive tissues, as well as the developmental stages at which it is activated in soybean, remain unknown. Here, we report that DT occurs at most nodes (leaf developmental stages) of soybean plants subjected to WD + HS, and that it can function under extreme conditions of WD + HS (i.e., 18% of field water capacity and 42°C combined). Our findings reveal that DT is an effective acclimation strategy that protects reproductive processes from extreme conditions of WD + HS at almost all developmental stages. In addition, our findings suggest that, under field conditions, DT could also be active in plants subjected to low or mild levels of WD during a heat wave.

Mechanisms of plant acclimation to multiple abiotic stresses

Plants frequently encounter a range of abiotic stresses and their combinations. Even though stresses rarely occur in isolation, research on plant stress resilience typically focuses on single environmental stressors. Plant responses to abiotic stress combinations are often distinct from corresponding individual stresses. Factors determining the outcomes of combined stresses are complex and multifaceted. In this review, we summarize advancements in our understanding of the mechanisms underlying plant responses to co-occurring (combined and sequential) abiotic stresses, focusing on morphological, physiological, developmental, and molecular aspects. Comprehensive understanding of plant acclimation, including the signaling and response mechanisms to combined and individual stresses, can contribute to the development of strategies for enhancing plant resilience in dynamic environments.

Integration of multi-omics data and deep phenotyping provides insights into responses to single and combined abiotic stress in potato

Potato (Solanum tuberosum) is highly water and space efficient but susceptible to abiotic stresses such as heat, drought, and flooding, which are severely exacerbated by climate change. Our understanding of crop acclimation to abiotic stress, however, remains limited. Here, we present a comprehensive molecular and physiological high-throughput profiling of potato (Solanum tuberosum, cv. Désirée) under heat, drought, and waterlogging applied as single stresses or in combinations designed to mimic realistic future scenarios. Stress responses were monitored via daily phenotyping and multi-omics analyses of leaf samples comprising proteomics, targeted transcriptomics, metabolomics, and hormonomics at several timepoints during and after stress treatments. Additionally, critical metabolites of tuber samples were analyzed at the end of the stress period. We performed integrative multi-omics data analysis using a bioinformatic pipeline that we established based on machine learning and knowledge networks. Waterlogging produced the most immediate and dramatic effects on potato plants, interestingly activating ABA responses similar to drought stress. In addition, we observed distinct stress signatures at multiple molecular levels in response to heat or drought and to a combination of both. In response to all treatments, we found a downregulation of photosynthesis at different molecular levels, an accumulation of minor amino acids, and diverse stress-induced hormones. Our integrative multi-omics analysis provides global insights into plant stress responses, facilitating improved breeding strategies toward climate-adapted potato varieties.

Exploring Plant Resilience Through Secondary Metabolite Profiling: Advances in Stress Response and Crop Improvement

The metabolome, encompassing small molecules within organisms, provides critical insights into physiology, environmental influences, and stress responses. Metabolomics enables comprehensive analysis of plant metabolites, uncovering biomarkers and mechanisms underlying stress adaptation. Regulatory genes such as MYB and WRKY are central to secondary metabolite synthesis and environmental resilience. By integrating metabolomics with genomics, researchers can explore stress-related pathways and advance crop improvement efforts. This review examines metabolomic profiling under stress conditions, emphasizing drought tolerance mechanisms mediated by amino acids and organic acids. Additionally, it highlights the shikimate pathway's pivotal role in synthesizing amino acids and secondary metabolites essential for plant defense. These insights contribute to understanding metabolic networks that drive plant resilience, informing strategies for agricultural sustainability.

Physiological, molecular, and metabolic adaptations of plants to combined salinity and high irradiance stress

Global warming is expected to drive climate change, intensifying extreme weather events and aggravating stress conditions for plants due to the heightened frequency and severity of environmental factors. Among these stresses, the interplay of salinity and high irradiance is particularly critical, as it poses significant threats to crop productivity, food quality, and overall global food security. This review provides a comprehensive analysis of the physiological, molecular, and metabolic responses of various plant species to salinity (S), high irradiance (HL), and their combined stress (S + HL), highlighting the adaptative mechanisms plants employ to mitigate these adverse conditions. This study integrates in silico data, focusing on gene expression profiles and functional classification using Gene Ontology (GO) terms and analysis of transcription factor (TF) families such as MYB, WRKY and bHLH. Alongside gene expression data, we incorporated analyses of growth, development, and metabolism profiles across different species exposed to S, HL and S + HL. The findings point to adaptive mechanisms crucial for resilience, including reconfigurations in gene expression patterns, metabolic pathways and phytohormone profiles, demonstrating their potential in the development of climate-resilient crops. This review offers a framework for further research into multi-stress adaptation strategies. In addition, the importance of advancing crop resilience through these insights, contributing to the development of innovative approaches for sustainable agriculture in a rapidly changing climate, is outlined.

Molecular aspects of heat stress sensing in land plants

Heat stress impacts all aspects of life, from evolution to global food security. Therefore, it becomes essential to understand how plants respond to heat stress, especially in the context of climate change. The heat stress response (HSR) involves three main components: sensing, signal transduction, and cellular reprogramming. Here, I focus on the heat stress sensing component. How can cells detect heat stress if it is not a signalling particle? To answer this question, I have looked at the molecular definition of heat stress. It can be defined as any particular rise in the optimum growth temperature that leads to higher-than-normal levels of reactive molecular species and macromolecular damage to biological membranes, proteins, and nucleic acid polymers (DNA and RNA). It is precisely these stress-specific alterations that are detected by heat stress sensors, upon which they would immediately trigger the appropriate level of the HSR. In addition, the work towards thermotolerance is complemented by a second type of response, here called the cellular homeostasis response (CHR). Upon mild and extreme temperature changes, the CHR is triggered by plant thermosensors, which are responsible for monitoring temperature information. Heat stress sensors and thermosensors are distinct types of molecules, each with unique modes of activation and functions. While many recent reviews provide a comprehensive overview of plant thermosensors, there remains a notable gap in the review literature regarding an in-depth analysis of plant heat stress sensors. Here, I attempt to summarise our current knowledge of the cellular sensors involved in triggering the plant HSR.

Warm temperature and mild drought remodel transcriptome and alter Arabidopsis responses to mite herbivory

In the context of climate change, increased temperature and decreased water availability are expected to have profound effects on plant-herbivore interactions. To gain further insight into this issue, this work focuses on the dissection of the response of the Arabidopsis thaliana plant to the mite pest Tetranychus urticae under environmental conditions that resemble climate change. Phenotypical and molecular changes were analyzed in plants grown under mild drought and/or warm temperatures. When the transcriptome results were compared in standard and altered climate conditions, a large number of genes were found to be differentially expressed. Mite infestations in these plants showed that basal alterations conditioned the subsequent response of the plant to a specific biotic stressor. Warm temperatures favored mite performance and decreased jasmonic acid accumulation. Reduced plant damage in mild drought conditions was correlated with a higher jasmonic acid accumulation and the up-regulation of many genes involved in the production of defensive compounds. In conclusion, the use of ambient conditions that resemble climate change highlighted the drastic alterations in gene expression that may occur in nature. Understanding how these changes affect specific plant-herbivore interactions is crucial to determining how global warming will affect crop production in the future.

Transcriptome Analysis and Resistance Identification of bar and BPH9 Co-Transformation Rice

Insect pests and weeds are the two major biotic factors affecting crop yield in the modern agricultural system. In this study, a brown planthopper (BPH) resistance gene (BPH9) and glufosinate tolerance gene (bar) were stacked into a single T-DNA cassette and transformed into an indica rice (Oryza sativa L.) line H23. The present study employed a gene stacking process that combines more than one gene/trait into an individual transgenic plant to meet the increasing cropping demands under complex conditions. The transgenic rice H23 (H23R) co-expressing bar and BPH9 genes demonstrated both glufosinate tolerance and BPH resistance. We utilized transcriptome data to reveal the mechanism of BPH9-mediated brown planthopper resistance and to analyze the impact of exogenous transgenic fragments on upstream and downstream genes at insertion sites. The evaluation of insect resistance and glufosinate tolerance confirmed H23R as an excellent double-resistant transgenic rice. These findings indicate that H23R can satisfy insect management and weed control in the modern rice agricultural system. However, a deregulation study will help with prospective commercial planting.

Identification of genes involved in the tomato root response to Globodera rostochiensis parasitism under varied light conditions

Understanding the intricate interplay between abiotic and biotic stresses is crucial for deciphering plant responses and developing resilient cultivars. Here, we investigate the combined effects of elevated light intensity and nematode infection on tomato seedlings. Chlorophyll fluorescence analysis revealed significant enhancements in PSII quantum yield and photochemical fluorescence quenching under high light conditions. qRT-PCR analysis of stress-related marker genes exhibited differential expression patterns in leaves and roots, indicating robust defense and antioxidant responses. Despite root protection from light, roots showed significant molecular changes, including downregulation of genes associated with oxidative stress and upregulation of genes involved in signaling pathways. Transcriptome analysis uncovered extensive gene expression alterations, with light exerting a dominant influence. Notably, light and nematode response synergistically induced more differentially expressed genes than individual stimuli. Functional categorization of differentially expressed genes upon double stimuli highlighted enrichment in metabolic pathways, biosynthesis of secondary metabolites, and amino acid metabolism, whereas the importance of specific pathogenesis-related pathways decreased. Overall, our study elucidates complex plant responses to combined stresses, emphasizing the importance of integrated approaches for developing stress-resilient crops in the face of changing environmental conditions.

Manifold roles of potassium in mediating drought tolerance in plants and its underlying mechanisms

Drought stress (DS) is a major devastating factor affecting plant growth and development worldwide. Potassium (K) is considered a vigorous moiety and stress alleviator, which crop cultivars need for better yield. It is also helpful in alleviating the DS-induced negative consequences by regulating various morphological, physiological, biochemical, and molecular mechanisms in plants. Particularly, the K application improves plant tolerance against DS by improving plant growth parameters, photosynthetic pigments, cell turgor pressure, osmotic pressure, nutritional balance, compatible solutes, and the plant's antioxidant defense system. Apart from its role as a constituent of the plant structure, biochemical processes such as protein synthesis, carbohydrate metabolism, and enzyme activation are also regulated by K. However, the exact K-mediated molecular mechanisms of DS tolerance are still unclear and require more investigation. The present review aims to provide insight into the role of K in regulating various morphological and physico-chemical aspects under DS. It also emphasizes the crosstalk of K with other nutrients and phytohormones, as well as molecular mechanisms for K homeostasis under DS. We have also shed light on genomics analysis to discover K transporter's novel genes in different plant species.

Exploring the Role of Non-Structural Carbohydrates (NSCs) Under Abiotic Stresses on Woody Plants: A Comprehensive Review

Global climate change has increased the severity and frequency of abiotic stresses, posing significant challenges to the survival and growth of woody plants. Non-structural carbohydrates (NSCs), including starch and sugars, play a vital role in enabling plants to withstand these stresses, helping to stabilize cellular functions by buffering plant energy demands and facilitating recovery on the alleviation of stress. Despite the recognized multiple functions of NSCs, the contrasting effects of multiple abiotic stresses on NSCs dynamics in woody plants remain poorly understood. This review aims to explore the current knowledge of the contrasting effects of abiotic stress conditions including drought, salinity, heat, water logging, and cold on NSCs dynamics. The roles of NSCs in regulating stress-resilience responses in woody plants are also discussed, along with the challenges in NSC measurement, and options for future research directions are explored. This review is based on comprehensive literature research across different search engines like Scopus, Web of Science, and Google Scholar (2000-2024) using targeted keywords. This study compiles the current research on NSCs functions and provides insights into the adaptive strategies of woody plants in response to changing climate conditions, providing groundwork for future research to improve stress tolerance in woody plants.

No free entry: stomatal state as decision maker in defining stress response strategies

This article comments on:

Maleki FA, Seidl-Adams I, Felton GW, Kersch-Becker MF, Tumlinson JH. 2024. Stomata: gatekeepers of uptake and defense signaling by green leaf volatiles in maize. Journal of Experimental Botany 75, 6872–6887. https://doi.org/10.1093/jxb/erae401.

Response of Arabidopsis thaliana to Flooding with Physical Flow

Flooding causes severe yield losses worldwide, making it urgent to enhance crop tolerance to this stress. Since natural flooding often involves physical flow, we hypothesized that the effects of submergence on plants could change when combined with physical flow. In this study, we analyzed the growth and transcriptome of Arabidopsis thaliana exposed to submergence or flooding with physical flow. Plants exposed to flooding with physical flow had smaller rosette diameters, especially at faster flow rates. Transcriptome analysis revealed that "defense response" transcripts were highly up-regulated in response to flooding with physical flow. In addition, up-regulation of transcripts encoding ROS-producing enzymes, SA synthesis, JA synthesis, and ethylene signaling was more pronounced under flooding with physical flow when compared to submergence. Although H2O2 accumulation changed in response to submergence or flooding with physical flow, it did not lead to lipid peroxidation, suggesting a role for ROS as signaling molecules under these conditions. Multiple regression analysis indicated possible links between rosette diameter under flooding with physical flow and the expression of Rbohs and SA synthesis transcripts. These findings suggest that pathogen defense responses, regulated by SA and ROS signaling, play crucial roles in plant responses to flooding with physical flow.

Genetic Foundation of Leaf Senescence: Insights from Natural and Cultivated Plant Diversity

Leaf senescence, the final stage of leaf development, is crucial for plant fitness as it enhances nutrient reutilization, supporting reproductive success and overall plant adaptation. Understanding its molecular and genetic regulation is essential to improve crop resilience and productivity, particularly in the face of global climate change. This review explores the significant contributions of natural genetic diversity to our understanding of leaf senescence, focusing on insights from model plants and major crops. We discuss the physiological and adaptive significance of senescence in plant development, environmental adaptation, and agricultural productivity. The review emphasizes the importance of natural genetic variation, including studies on natural accessions, landraces, cultivars, and artificial recombinant lines to unravel the genetic basis of senescence. Various approaches, from quantitative trait loci mapping to genome-wide association analysis and in planta functional analysis, have advanced our knowledge of senescence regulation. Current studies focusing on key regulatory genes and pathways underlying natural senescence, identified from natural or recombinant accession and cultivar populations, are highlighted. We also address the adaptive implications of abiotic and biotic stress factors triggering senescence and the genetic mechanisms underlying these responses. Finally, we discuss the challenges in translating these genetic insights into crop improvement. We propose future research directions, such as expanding studies on under-researched crops, investigating multiple stress combinations, and utilizing advanced technologies, including multiomics and gene editing, to harness natural genetic diversity for crop resilience.

Decoding the Double Stress Puzzle: Investigating Nutrient Uptake Efficiency and Root Architecture in Soybean Under Heat- and Water-Stresses

In the context of climate change, associated with increasingly frequent water deficits and heat waves, there is an urgent need to maintain the performance of soybean, a leading legume crop worldwide, before its yield declines. The objective of this study was to explore which plant traits improve soybean tolerance to heat and/or water stress, with a focus on traits involved in plant architecture and nutrient uptake. For this purpose, two soybean genotypes were grown under controlled conditions in a high-throughput phenotyping platform where either optimal conditions, heat waves, water stress or both heat waves and water stresses were applied during the vegetative stage. By correlating architectural to functional traits, related to water, carbon allocation and nutrient absorption, we were able to explain the stress susceptibility level of the two genotypes. We have shown that water flow in the plant is central to the uptake and allocation of mineral elements in the plant, despite its modulation by stress and in a genotype-dependent manner. This cross-analysis of plant ecophysiology and plant nutrition under different stresses provides new information, especially on the importance of mineral elements in the different plant organs, and can inform future crop design, particularly under changing climatic conditions.

Unmasking complexities of combined stresses for creating climate-smart crops

Understanding the complex challenges that plants face from multiple stresses is key to developing climate-ready crops. We highlight the significance of the Stress Combinations and their Interactions in Plants database (SCIPdb) for studying the impact of stress combinations on plants and the importance of aligning thematic research programs to create crops aligned with achieving sustainable development goals.

Seasonal influence on tomato fruit metabolome profile: Implications for ABA signaling in multi-stress resilience

The increasing effects of climate change are leading to an increase in the number and intensity of extreme events, making it essential to study how plants respond to various stresses occurring simultaneously. A crucial regulator of plant responses to abiotic stress is abscisic acid (ABA), as its accumulation in response to stress leads to transcriptomic and metabolomic changes that contribute to plant stress tolerance. In the present study, we investigated how ABA, stress conditions (salinity, water deficit and their combination) and seasons (autumn-winter and spring-summer) regulate tomato fruit yield and metabolism using tomato wild type (WT) and the ABA-deficient flacca mutant (flc) under stress conditions in cold and warm seasons. Our results showed that the applied stresses did not have the same effect in the warm season as in the cold season. In WT plants, the levels of other flavonoids, lignans and other polyphenols were higher in summer fruits, whereas the levels of anthocyanins, flavanols, flavonols, phenolic acids and stilbenes were higher in winter fruits. Furthermore, the significant increase in anthocyanins and flavonols was associated with the combination of salinity + water deficit in both seasons. Additionally, under certain conditions, flc mutants showed an enrichment of the superclasses of benzenoids and organosulphur compounds. The synthesis of phenolic compounds in flc fruits was also significantly different compared to WT plants. Thus, the metabolic profile of tomato fruits varies significantly with endogenous ABA levels, season of cultivation and applied stress treatments, highlighting the multifactorial nature of plant responses to combined environmental factors.

Omics-Driven Strategies for Developing Saline-Smart Lentils: A Comprehensive Review

A number of consequences of climate change, notably salinity, put global food security at risk by impacting the development and production of lentils. Salinity-induced stress alters lentil genetics, resulting in severe developmental issues and eventual phenotypic damage. Lentils have evolved sophisticated signaling networks to combat salinity stress. Lentil genomics and transcriptomics have discovered key genes and pathways that play an important role in mitigating salinity stress. The development of saline-smart cultivars can be further revolutionized by implementing proteomics, metabolomics, miRNAomics, epigenomics, phenomics, ionomics, machine learning, and speed breeding approaches. All these cutting-edge approaches represent a viable path toward creating saline-tolerant lentil cultivars that can withstand climate change and meet the growing demand for high-quality food worldwide. The review emphasizes the gaps that must be filled for future food security in a changing climate while also highlighting the significant discoveries and insights made possible by omics and other state-of-the-art biotechnological techniques.

Gamma-aminobutyric acid elicits H2O2 signalling and promotes wheat seed germination under combined salt and heat stress

Background

In the realm of wheat seed germination, abiotic stresses such as salinity and high temperature have been shown to hinder the process. These stresses can lead to the production of reactive oxygen species, which, within a certain concentration range, may actually facilitate seed germination. γ-aminobutyric acid (GABA), a non-protein amino acid, serves as a crucial signaling molecule in the promotion of seed germination. Nevertheless, the potential of GABA to regulate seed germination under the simultaneous stress of heat and salinity remains unexplored in current literature.

Methods

This study employed observational methods to assess seed germination rate (GR), physiological methods to measure H2O2 content, and the activities of glutamate decarboxylase (GAD), NADPH oxidase (NOX), superoxide dismutase (SOD), and catalase (CAT). The levels of ABA and GABA were quantified using high-performance liquid chromatography technology. Furthermore, quantitative real-time PCR technology was utilized to analyze the expression levels of two genes encoding antioxidant enzymes, MnSOD and CAT.

Results

The findings indicated that combined stress (30 °C + 50 mM NaCl) decreased the GR of wheat seeds to about 21%, while treatment with 2 mM GABA increased the GR to about 48%. However, the stimulatory effect of GABA was mitigated by the presence of ABA, dimethylthiourea, and NOX inhibitor, but was strengthened by H2O2, antioxidant enzyme inhibitor, fluridone, and gibberellin. In comparison to the control group (20 °C + 0 mM NaCl), this combined stress led to elevated levels of ABA, reduced GAD and NOX activity, and a decrease in H2O2 and GABA content. Further investigation revealed that this combined stress significantly suppressed the activity of superoxide dismutase (SOD) and catalase (CAT), as well as downregulated the gene expression levels of MnSOD and CAT. However, the study demonstrates that exogenous GABA effectively reversed the inhibitory effects of combined stress on wheat seed germination. These findings suggest that GABA-induced NOX-mediated H2O2 signalling plays a crucial role in mitigating the adverse impact of combined stress on wheat seed germination. This research holds significant theoretical and practical implications for the regulation of crop seed germination by GABA under conditions of combined stress.

Heat Stress and Plant-Biotic Interactions: Advances and Perspectives

Climate change presents numerous challenges for agriculture, including frequent events of plant abiotic stresses such as elevated temperatures that lead to heat stress (HS). As the primary driving factor of climate change, HS threatens global food security and biodiversity. In recent years, HS events have negatively impacted plant physiology, reducing plant's ability to maintain disease resistance and resulting in lower crop yields. Plants must adapt their priorities toward defense mechanisms to tolerate stress in challenging environments. Furthermore, selective breeding and long-term domestication for higher yields have made crop varieties vulnerable to multiple stressors, making them more susceptible to frequent HS events. Studies on climate change predict that concurrent HS and biotic stresses will become more frequent and severe in the future, potentially occurring simultaneously or sequentially. While most studies have focused on singular stress effects on plant systems to examine how plants respond to specific stresses, the simultaneous occurrence of HS and biotic stresses pose a growing threat to agricultural productivity. Few studies have explored the interactions between HS and plant-biotic interactions. Here, we aim to shed light on the physiological and molecular effects of HS and biotic factor interactions (bacteria, fungi, oomycetes, nematodes, insect pests, pollinators, weedy species, and parasitic plants), as well as their combined impact on crop growth and yields. We also examine recent advances in designing and developing various strategies to address multi-stress scenarios related to HS and biotic factors.

Unique regulatory network of dragon fruit simultaneously mitigates the effect of vanadium pollutant and environmental factors

Under changing climatic conditions, plants are simultaneously facing conflicting stresses in nature. Plants can sense different stresses, induce systematic ROS signals, and regulate transcriptomic, hormonal, and stomatal responses. We performed transcriptome analysis to reveal the integrative stress response regulatory mechanism underlying heavy metal stress alone or in combination with heat and drought conditions in pitaya (dragon fruit). A total of 70 genes were identified from 31,130 transcripts with conserved differential expression. Furthermore, weighted gene co-expression network analysis (WGCNA) identified trait-associated modules. By integrating information from three modules and protein-protein interaction (PPI) networks, we identified 10 interconnected genes associated with the multifaceted defense mechanism employed by pitaya against co-occurring stresses. To further confirm the reliability of the results, we performed a comparative analysis of 350 genes identified by three trait modules and 70 conserved genes exhibiting their dynamic expression under all treatments. Differential expression pattern of genes and comparative analysis, have proven instrumental in identifying ten putative structural genes. These ten genes were annotated as PLAT/LH2, CAT, MLP, HSP, PB1, PLA, NAC, HMA, and CER1 transcription factors involved in antioxidant activity, defense response, MAPK signaling, detoxification of metals and regulating the crosstalk between the complex pathways. Predictive analysis of putative candidate genes, potentially governing single, double, and multifactorial stress response, by several signaling systems and molecular patterns. These findings represent a valuable resource for pitaya breeding programs, offering the potential to develop resilient "super pitaya" plants.

Elevated [CO2] and temperature augment gas exchange and shift the fitness landscape in a montane forb

Climate change is simultaneously increasing carbon dioxide concentrations ([CO2]) and temperature. These factors could interact to influence plant physiology and performance. Alternatively, increased [CO2] may offset costs associated with elevated temperatures. Furthermore, the interaction between elevated temperature and [CO2] may differentially affect populations from along an elevational gradient and disrupt local adaptation. We conducted a multifactorial growth chamber experiment to examine the interactive effects of temperature and [CO2] on fitness and ecophysiology of diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado. We tested whether increased [CO2] would enhance photosynthesis across accessions, and whether warmer conditions would depress the fitness of high-elevation accessions owing to steep reductions in temperature with increasing elevation in this system. Elevational clines in [CO2] are not as evident, making it challenging to predict how locally adapted ecotypes will respond to elevated [CO2]. This experiment revealed that elevated [CO2] increased photosynthesis and intrinsic water use efficiency across all accessions. However, these instantaneous responses to treatments did not translate to changes in fitness. Instead, increased temperatures reduced the probability of reproduction for all accessions. Elevated [CO2] and increased temperatures interacted to shift the adaptive landscape, favoring lower elevation accessions for the probability of survival and fecundity. Our results suggest that elevated temperatures and [CO2] associated with climate change could have severe negative consequences, especially for high-elevation populations.

Impact of Biotic/Abiotic Stress Factors on Plant Specialized Metabolites

Plants are a group of organisms that have developed remarkable adaptations to merely exist in the environment [...].

Creating Climate-Resilient Crops by Increasing Drought, Heat, and Salt Tolerance

Over the years, the changes in the agriculture industry have been inevitable, considering the need to feed the growing population. As the world population continues to grow, food security has become challenged. Resources such as arable land and freshwater have become scarce due to quick urbanization in developing countries and anthropologic activities; expanding agricultural production areas is not an option. Environmental and climatic factors such as drought, heat, and salt stresses pose serious threats to food production worldwide. Therefore, the need to utilize the remaining arable land and water effectively and efficiently and to maximize the yield to support the increasing food demand has become crucial. It is essential to develop climate-resilient crops that will outperform traditional crops under any abiotic stress conditions such as heat, drought, and salt, as well as these stresses in any combinations. This review provides a glimpse of how plant breeding in agriculture has evolved to overcome the harsh environmental conditions and what the future would be like.

Systemic stomatal responses in plants: Coordinating development, stress, and pathogen defense under a changing climate

To successfully survive, develop, grow and reproduce, multicellular organisms must coordinate their molecular, physiological, developmental and metabolic responses among their different cells and tissues. This process is mediated by cell-to-cell, vascular and/or volatile communication, and involves electric, chemical and/or hydraulic signals. Within this context, stomata serve a dual role by coordinating their responses to the environment with their neighbouring cells at the epidermis, but also with other stomata present on other parts of the plant. As stomata represent one of the most important conduits between the plant and its above-ground environment, as well as directly affect photosynthesis, respiration and the hydraulic status of the plant by controlling its gas and vapour exchange with the atmosphere, coordinating the overall response of stomata within and between different leaves and tissues plays a cardinal role in plant growth, development and reproduction. Here, we discuss different examples of local and systemic stomatal coordination, the different signalling pathways that mediate them, and the importance of systemic stomatal coordination to our food supply, ecosystems and weather patterns, under our changing climate. We further discuss the potential biotechnological implications of regulating systemic stomatal responses for enhancing agricultural productivity in a warmer and CO2 -rich environment.

The impact of multifactorial stress combination on reproductive tissues and grain yield of a crop plant

Global warming, climate change, and industrial pollution are altering our environment subjecting plants, microbiomes, and ecosystems to an increasing number and complexity of abiotic stress conditions, concurrently or sequentially. These conditions, termed, "multifactorial stress combination" (MFSC), can cause a significant decline in plant growth and survival. However, the impacts of MFSC on reproductive tissues and yield of major crop plants are largely unknown. We subjected soybean (Glycine max) plants to a MFSC of up to five different stresses (water deficit, salinity, low phosphate, acidity, and cadmium), in an increasing level of complexity, and conducted integrative transcriptomic-phenotypic analysis of their reproductive and vegetative tissues. We reveal that MFSC has a negative cumulative effect on soybean yield, that each set of MFSC condition elicits a unique transcriptomic response (that is different between flowers and leaves), and that selected genes expressed in leaves or flowers of soybean are linked to the effects of MFSC on different vegetative, physiological, and/or reproductive parameters. Our study identified networks and pathways associated with reactive oxygen species, ascorbic acid and aldarate, and iron/copper signaling/metabolism as promising targets for future biotechnological efforts to augment the resilience of reproductive tissues of major crop plants to MFSC. In addition, we provide unique phenotypic and transcriptomic datasets for dissecting the mechanistic effects of MFSC on the vegetative, physiological, and reproductive processes of a crop plant.

Transcriptomics, proteomics, and metabolomics interventions prompt crop improvement against metal(loid) toxicity

The escalating challenges posed by metal(loid) toxicity in agricultural ecosystems, exacerbated by rapid climate change and anthropogenic pressures, demand urgent attention. Soil contamination is a critical issue because it significantly impacts crop productivity. The widespread threat of metal(loid) toxicity can jeopardize global food security due to contaminated food supplies and pose environmental risks, contributing to soil and water pollution and thus impacting the whole ecosystem. In this context, plants have evolved complex mechanisms to combat metal(loid) stress. Amid the array of innovative approaches, omics, notably transcriptomics, proteomics, and metabolomics, have emerged as transformative tools, shedding light on the genes, proteins, and key metabolites involved in metal(loid) stress responses and tolerance mechanisms. These identified candidates hold promise for developing high-yielding crops with desirable agronomic traits. Computational biology tools like bioinformatics, biological databases, and analytical pipelines support these omics approaches by harnessing diverse information and facilitating the mapping of genotype-to-phenotype relationships under stress conditions. This review explores: (1) the multifaceted strategies that plants use to adapt to metal(loid) toxicity in their environment; (2) the latest findings in metal(loid)-mediated transcriptomics, proteomics, and metabolomics studies across various plant species; (3) the integration of omics data with artificial intelligence and high-throughput phenotyping; (4) the latest bioinformatics databases, tools and pipelines for single and/or multi-omics data integration; (5) the latest insights into stress adaptations and tolerance mechanisms for future outlooks; and (6) the capacity of omics advances for creating sustainable and resilient crop plants that can thrive in metal(loid)-contaminated environments.

Plant biology: Unlocking mitochondrial stress signals

Environmental stress induces mitochondrial retrograde signals that prompt protective responses in plants. The elusive mitochondrial signal has now been uncovered in a new study, which identifies formation of reactive oxygen species inside mitochondria as the key trigger of stress signals.