Drought and heat stress mediated activation of lipid signaling in plants: a critical review

Transcriptomics Reveals an Energy-Saving Metabolic Switch in an Extremophilic Red Microalga Cyanidioschyzon merolae Under Nickel Stress

The red microalga Cyanidioschyzon merolae inhabits extreme environments with high temperatures (40-56 °C), high acidity (pH 0.05-4), and high concentrations of heavy metals that are lethal to most forms of life. However, information is scarce on the precise adaptation mechanisms of this extremophile to such hostile conditions. Gaining such knowledge is important for understanding the evolution of microorganisms in the early stages of life on Earth characterized by such extreme environments. Through an analysis of the re-programming of the global transcriptome upon the long-term (up to 15 days) exposure of C. merolae to extremely high concentrations of nickel (1 and 3 mM), the key adaptive metabolic pathways and associated molecular components were identified. Our work shows that the long-term Ni exposure of C. merolae leads to the lagged metabolic switch demonstrated via the transcriptional upregulation of the metabolic pathways critical for cell survival. DNA replication, cell cycle, and protein quality control processes were upregulated, while downregulation occurred with energetically costly processes, including the assembly of the photosynthetic apparatus and lipid biosynthesis. This study paves the way for future multi-omic studies of the molecular mechanisms of abiotic stress adaptation in phototrophs, as well as the future development of rational approaches to the bioremediation of contaminated aquatic environments.

Unveiling regional and altitudinal lipidomic analyte signatures of the argan tree (Argania spinosa L.) for environmental adaptation

Environmental factors such as altitude, precipitation, and temperature shape the lipidomic profiles of the argan tree (Argania spinosa L.), supporting its adaptation to stress. This study investigated lipidomic profiling and pathways in argan tree leaves from four altitudinal zones (A: low, B: moderate, C: high, D: very high) across three Moroccan regions (Chtouka Aït Baha, Essaouira, and Tiznit) using Gas Chromatography-Mass Spectrometry (GC-MS). The GC-MS workflow included a transmethylation step that cleaves ester bonds and acetylations, yielding analytes derived from diverse precursor lipids such as glycerolipids, sterol esters, and wax esters. We identified 139 lipid analytes, categorized into fatty acyls (53 %), prenol lipids (41 %), and steroids (6 %). Shared lipids across all zones highlight core metabolic pathways essential for resilience, while unique lipids reflect zone-specific adaptations. Fourteen known analytes were identified as critical markers for regional adaptations through multivariate analyses, including Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS-DA), and Variable Importance in Projection (VIP) scores. Among these, three analytes (methyl 18-methyleicosanoate, Z,Z-11,13-Hexadecadien-1-ol, and 11-Octadecenoic acid) showed the highest accumulation in Zone A, whereas eleven analytes (Henicosyl formate, Dodecyl 2-methylbutanoate, Methyl 21-methyl-hexacosanoate, Methyl 13-methyltetradecanoate, Cetoleic acid, (Urs-12-en-3-ol, acetate, (3.beta.)-), Medicagenic acid, 2-(4a,8-Dimethyl-6-oxo-1,2,3,4,4a,5,6,8a-octahydro-naphthalen-2-yl)-propionaldehyde, A'-Neogammacer-22(29)-en-3-one, Pregna-5,17(20)-dien-3-ol, (3.beta.,17E)-, and estra-1,3,5(10)-trien-17-one, 3,4-bis(acetyloxy)- exhibited significant increases in Zone D. Multiple Linear Regression analysis showed that precipitation positively influenced analyte concentration (p = 0.00033), while altitude had a significant negative effect (p = 0.039). Pathways analysis highlighted the roles of cutin, suberin, and wax biosynthesis, as well as linoleic acid metabolism, in altitude-driven adaptations. This study demonstrates the metabolic plasticity of Argania spinosa L., offering insights for its conservation amidst climate change.

A novel stress-inducible dCas9 system for solanaceous plants

Conditional manipulation of gene expression is essential in plant biology, yet a simple stimuli-based inducible system for regulating any plant gene is lacking. Here, we present an innovative stress-inducible CRISPR/dCas9-based gene-regulatory toolkit tailored for intentional gene regulation in solanaceous plants. We have translationally fused the transmembrane domain of a tomato membrane-bound NAC transcription factor with dCas9 to utilize the reversible-tethering-based activation mechanism. This system sequesters dCas9 to the plasma membrane under normal conditions and allows membrane detachment in response to heat induction and NLS-mediated nuclear transfer, enabling stress-inducible gene regulation. Transient assays with tomato codon-optimized dCas9-assisted inducible CRISPR activation and interference systems confirmed their superior ability on transcriptional control, rapid induction, and reversibility after stimulus withdrawal in solanaceous plants. The transformative potential of the toolkit was exemplified by enhancing tomato immunity against bacterial speck disease under elevated temperatures by precisely regulating crucial salicylic acid signalling components, SlCBP60g and SlSARD1. Additionally, it was instrumental in engineering heat-stress tolerance in tomato plants through multiplex activation of heat-responsive transcription factors, SlNAC2 and SlHSFA6b. These findings demonstrate the unprecedented temporal control offered by this novel stress-inducible toolkit over gene-expression dynamics, paving the way for favourable manipulation of complex traits in environmentally-challenged crops.

Reclaiming Wolffia arrhiza as fish feed for the phytoremediation of aquaculture effluent

The aquaculture industry through the fisheries sector holds an important key aspect of food security. Despite its significance, it comes with environmental issues that cannot be avoided in most industrial activities, especially issues regarding water-related pollution. This study explores a novel dual-purpose approach, in which a floating species, Wolffia arrhizal, was applied for phyto-remediating aquaculture effluent and later followed by the evaluation of its potential as alternative fish feed. Different concentrations of contaminant loads were exposed to W. arrhiza plants for 7 days, and the best performance with removals of 15 % chemical oxygen demand (COD), 80 % biological oxygen demand (BOD), 99 % ammoniacal nitrogen (AN) and 94 % total suspended solids (TSS) were achieved in the treatment system using 0.1 g COD/g plant. The harvested plant biomass enriched with nutrients demonstrating strong potential for resource recovery within a circular economy framework, was then utilized in three separate fish feeding trials. Catfish were fed with 100 % commercial pallets; 50 % mixture of commercial pallets and 50 % W. arrhizal; and 100 % W. arrhiza. Results showed that W. arrhiza collected after phytoremediation treatment shows good potential as fish feed, but modification is needed in its formulation to ensure sufficient nutrient supply for fishes. This study highlights the dual potential of W. arrhiza as phytoremediator for aquaculture effluent and later being used as fish feed, contributing to both environmental protection and resource circularity in aquaculture.

Metabolomic responses of wheat grains to olive mill wastewater and drought stress treatments

The present research aimed to assess the metabolomic responses of wheat to olive mill wastewater (OMWW) and drought stress treatments. Wheat plants were cultivated under controlled conditions with the following treatments: control (75% field capacity, FC), OMWW (75 ml L-1), drought stress (40% FC, applied 30 days after sowing), and a combined treatment of OMWW and drought stress. Drought stress alone reduced grain yield by 67%, while the OMWW-treated plants resulted in a 29% reduction under stress relative to the control. OMWW application improved soil properties, enhancing organic matter and nutrient levels. Wheat grains from OMWW-treated plants exhibited higher sugar content and related enzyme activities, indicating improved metabolism, with significant increases in starch, fructose, and glucose levels alongside stable invertase and sucrose phosphate synthase activities. The study also noted substantial changes in amino acids, fatty acids, and phenolic acids in plants subjected to OMWW and drought stress. These modifications indicate OMWW's capability to influence vital biochemical pathways and boost antioxidant capacities in wheat. In conclusion, OMWW proves to be an effective soil amendment that mitigates drought stress and contributes to the production of nutrient-rich, resilient wheat, underscoring its potential as a sustainable agricultural practice in water-scarce areas.

Identification of novel candidate genes for regulating oil composition in soybean seeds under environmental stresses

Introduction

A key objective of soybean breeding programs is to enhance nutritional quality for human and animal consumption, with improved fatty acid (FA) composition for health benefits, and expand soybean use for industrial applications.

Methods

We conducted a metabolite genome-wide association study (mGWAS) to identify genomic regions associated with changes in FA composition and FA ratios in soybean seeds influenced by environmental factors. This mGWAS utilized 218 soybean plant introductions (PIs) grown in two field locations in Virginia over two years.

Results

The mGWAS revealed that 20 SNPs were significantly associated with 21 FA ratios, while additional suggestive SNPs were found for 36 FA ratios, highlighting potential quantitative trait loci linked to FA composition.

Discussion

Many of these SNPs are located near or within the genes related to phytohormone-mediated biotic and abiotic stress responses, suggesting the involvement of environmental factors in modulating FA composition in soybean seeds. Our findings provide novel insights into the genetic and environmental factors influencing FA composition in oilseeds. This research also lays the foundation for developing stable markers to develop soybean cultivars with tailored FA profiles for different practical applications under variable growth conditions.

Leaf drought and heat tolerance are integrated across three temperate biome types

Leaf-scale heat and drought tolerance provide direct measures of the ability to withstand environmental stress and can be used to evaluate plant susceptibility to emerging climatic extremes. However, recent droughts increasingly occur with heatwaves, causing plants to withstand two simultaneous environmental stresses. Tolerance of leaf-level processes to heat and drought stress have mostly been studied independently, preventing an understanding of whether tolerance co-occurs for these two environmental stresses. To address this, we measured leaf photosynthetic heat tolerance as the critical temperatures at which photosystem II efficiency starts to decrease (Tcrit) and shows a decrease of 50% (T50) or 95% (T95) in three temperate biomes (desert, oak-pine forest, and mediterranean-type shrubland). We also characterized drought tolerance as the water potential at leaf turgor loss point (πtlp) and cellular membrane stability in response to simulated drought. We found coordination of heat and drought tolerance through a significant relationship of πtlp with T50 and Tcrit that varied with season, whereas T95 showed no relation to πtlp. Species with greater drought tolerance also showed greater membrane stability, implicating membrane leakiness as a potential mechanism of physiological decline during stress. Despite local variation in temperature and precipitation extremes, leaf heat and drought tolerance converged to common cross-biome relationships, providing evidence of interdependence that spanned distinct climates.

Light-driven modulation of plant response to water deficit. A review

The dependence of agriculture on water availability is an important premise justifying attempts to enhance water use efficiency for plant production. Photosynthetic efficiency, directly impacts biomass production, is dependent on both water availability and the quality and quantity of light. Understanding how these factors interact is crucial for improving crop yields. Many overlapping signalling pathways and functions of common bioactive molecules that shape plant responses to both water deficit and light have been identified and discussed in this review. Separate or combined action of these environmental factors include the generation of reactive oxygen species, biosynthesis of abscisic acid, stomatal functioning, chloroplast movement and alterations in the levels of photosynthetic pigments and bioactive molecules. Plant response to water deficit depends on light intensity and its characteristics, with differentiated impacts from UV, blue, and red light bands determining the strength and synergistic or antagonistic nature of interactions. Despite its significance, the combined effects of these environmental factors remain insufficiently explored. The findings highlight the potential for optimising horticultural production through controlled light conditions and regulated deficit irrigation. Future research should assess light and water manipulation strategies to enhance resource efficiency and crop nutritional value.

Plant sphingolipids: Subcellular distributions and functions

Sphingolipids are common membrane components that maintain membrane structural integrity and function as signaling molecules. Different sphingolipids have specific functions and are unevenly distributed across the membranes of various organelles and subcellular compartments. In this review, we survey the sphingolipidomes of different subcellular structures in Arabidopsis (Arabidopsis thaliana) cells and provide a detailed account of the functions of specific sphingolipids at each location. For example, glycosphingolipids, including glucosylceramide and glycosyl inositol phosphoceramide, mainly function in membranes, whereas simple sphingolipids, including free long-chain bases and ceramide, may have important signaling roles in the plasma membrane, mitochondria, and nucleus during plant stress responses and cell death. This review thus offers a broad perspective of the multifaceted roles of plant sphingolipids in different locations in the plant cell.

Heat stress in plants: sensing, signalling, and ferroptosis

In the current context of global warming, high temperature events are becoming more frequent and intense in many places around the world. In this context, understanding how plants sense and respond to heat is essential to develop new tools to prevent plant damage and address global food security, as high temperature events are threatening agricultural sustainability. This review summarizes and integrates our current understanding underlying the cellular, physiological, biochemical, and molecular regulatory pathways triggered in plants under moderately high and extremely high temperature conditions. Given that extremely high temperatures can also trigger ferroptosis, the study of this cell death mechanism constitutes a strategic approach to understand how plants might overcome otherwise lethal temperature events.

Flash drought as possible contributor to seedling dieback in the endangered conifer Abies koreana

Tree species grown at high altitudes experience significantly greater stress than those at lower altitudes. A notable example is Abies koreana, a conifer recently classified as endangered due to a decline in normal seedling distribution within Korean natural forests. While several hypotheses have been proposed to explain this phenomenon, the underlying causes remain unclear. Recent studies highlight that Korean forest tree species are increasingly vulnerable to flash drought (FD) events. However, it is still unknown whether this intense FD event affects the growth and distribution of high-altitude grown and endangered species like Abies koreana. To address this gap, we investigated the effects of FD on root carbon allocation, volatile biosynthesis, fatty acid modulation, and genome-wide modifications. Exposure to FD in three-year-old A. koreana seedlings primarily disrupted leaf chlorophyll biosynthesis, likely due to the depletion of root water and non-structural carbohydrates (NSC) transport to above-ground parts. Additionally, FD caused severe morphological changes, including reductions in root collar diameter along with root cortical senescence. These alterations are linked to transcriptomic variations, particularly mRNA decay and the repression of genes coding for ribosomal proteins. Seedlings exposed to FD also exhibited increased levels of abscisic acid (ABA) and poly-unsaturated fatty acids. The observed patterns and molecular mechanisms in FD-treated seedlings differed significantly from those observed for control and mild drought (MD) treatments. These findings suggest that FD conditions trigger rapid carbon reserve depletion and gene repression associated with root structural integrity, potentially leading to seedling mortality in Abies koreana seedlings.

Comprehensive analysis of the LTPG gene family in willow: Identification, expression profiling, and stress response

The non-specific lipid-transfer proteins (LTPs), particularly the glycosylphosphatidylinositol (GPI)-anchored LTPs (LTPGs), play pivotal roles in various plant physiological functions, particularly in the context of environmental stress adaptation. Despite their importance, LTPGs in willow (Salix matsudana), an ecologically and economically important species, remains poorly understood. This study systematically identified and characterized 30 SmLTPGs in the S. matsudana genome, classifying them into four distinct classes based on phylogenetic analysis. Tandem and segmental duplications in SmLTPGs highlighted their evolutionary diversification. Expression profiling revealed dynamic changes across various willow varieties and significant roles for SmLTPG24/25 and SmLTPG05 in salt and submergence stress responses, respectively. Additionally, co-expression analysis indicated a potential collaboration between SmLTPGs, fatty acid desaturases (FADs), and long-chain acyl-CoA synthetases (LACSs) in FA biosynthesis, contributing to resilience against salt and submergence stresses. This research provided critical insights into the molecular mechanisms underlying willow adaptability to environmental stresses and established a foundation for future applications in stress-tolerant willow breeding and management.

Metabolomic approaches suggest two mechanisms of drought response post-anthesis in Mediterranean oat (Avena sativa L.) cultivars

Oats (Avena sativa L) is a temperate cereal and an important healthy cereal cultivated for food and feed. Therefore, understanding drought responses in oats could significantly impact oat production under harsh climatic conditions. In particular, drought during anthesis (flowering) affects grain filling, quality and yield. Here, we characterised metabolite responses of two Mediterranean oat (Avena sativa L.) cultivars, Flega and Patones, during drought stress at anthesis. In the more drought-tolerant Patones, the developing grains from the top (older) and bottom (younger) spikelets of primary panicle were found to be larger in size in response to drought, suggesting accelerated grain development. Flega showed a more rapid transition to flowering and grain development under drought. The metabolomes of source (sheath, flag leaf, rachis) and sink (developing grains) tissues from Patones showed differential accumulation in fatty acids levels, including α-linolenic acid, sugars and amino acids with drought. Flega showed enhanced energy metabolism in both source and sink tissues. Lower levels of glutathione in source tissues and the accumulation of ophthalmic acid in the grains of Flega were indicators of oxidative stress. Our study revealed two distinct metabolite regulatory patterns in these cultivars during drought at anthesis. In Patones, α-linolenic acid-associated processes may accelerate grain-filling, while in Flega oxidative stress appears to influence traits such as flowering time. Overall, this work provides a first insight into the metabolite regulation in oat's source and sink tissues during anthesis under drought stress.

Tolerance to combined drought and heat stress in edamame is associated with enhanced antioxidative responses and cell wall modifications

Drought and heat stress often co-occur in nature, and their combined effects are a major driver of crop losses, causing more severe damage to plant metabolism than when they occur individually. This study investigates the responses of three edamame cultivars (AGS429, UVE14, and UVE17) to combined drought and heat (DH) stress, with emphasis on the reactive oxygen species (ROS), antioxidative mechanisms and cell wall modifications. Malondialdehyde (MDA), electrolyte leakage (EL), and hydrogen peroxide (H2O2) were used to measure oxidative stress and membrane damage. The non-enzymatic (ascorbic acid, AsA) and enzymatic (superoxide dismutase, ascorbate peroxidase (APX), guaiacol peroxidase, and glutathione reductase) antioxidant responses were determined spectrophotometrically. Cell wall biomass composition (cellulose, hemicellulose, lignin, and phenols) was determined using Fourier transform Infrared Spectroscopy and spectrophotometry. Ascorbate peroxidase activity and AsA content in DH-stressed AGS429 at flowering strongly correlated to reduced lipid peroxidation (r2 = -0.97 and - 0.98). Cultivar UVE14 accumulated high AsA under DH stress at both growth stages, which, in turn, was positively associated with total phenolic content (r2 = 0.97), APX activity, and holocellulose, suggesting enhanced ROS-dependent oxidative polymerisation. On the contrary, poor ROS quenching in UVE17 led to MDA accumulation (p ≤ 0.05), leading to high EL and poor cellulose synthesis at pod-filling (r2 = -0.88). Therefore, at the physio-biochemical level, AGS429 and UVE14 showed DH stress tolerance through enhanced antioxidative responses and cell wall modifications, while UVE17 was susceptible. Identifying the key biochemical traits linked to DH stress tolerance in edamame offers novel insights for breeding more resilient edamame cultivars.

Date palm diverts organic solutes for root osmotic adjustment and protects leaves from oxidative damage in early drought acclimation

Date palm (Phoenix dactylifera L.) is an important crop in arid regions and it is well adapted to desert ecosystems. To understand its remarkable ability to grow and yield in water-limited environments, we conducted experiments in which water was withheld for up to 4 weeks. In response to drought, root, rather than leaf, osmotic strength increased, with organic solutes such as sugars and amino acids contributing more to the osmolyte increase than minerals. Consistently, carbon and amino acid metabolism was acclimated toward biosynthesis at both the transcriptional and translational levels. In leaves, a remodeling of membrane systems was observed, suggesting changes in thylakoid lipid composition which, together with the restructuring of the photosynthetic apparatus, indicated an acclimation preventing oxidative damage. Thus, xerophilic date palm avoids oxidative damage under drought by combined prevention and rapid detoxification of oxygen radicals. Although minerals were expected to serve as cheap key osmotics, date palm also relies on organic osmolytes for osmotic adjustment in the roots during early drought acclimation. The diversion of these resources away from growth is consistent with the date palm strategy of generally slow growth in harsh environments and clearly indicates a trade-off between growth and stress-related physiological responses.

The Impact of Temperature on the Leaves of Ceratonia siliqua L.: Anatomical Aspect, Secondary Metabolite Analysis, and Antimicrobial Activity of the Extracts

Ceratonia siliqua L. (Fabaceae) is an evergreen sclerophyllous species that successfully overcomes the challenges of the Mediterranean climate. Commonly, biosynthesis of secondary metabolites is a major reaction of the plants thriving in the Mediterranean formations against temperature stress. Due to concerns about the climate crisis, we studied the impact of 6-day low (5 °C) and high (40 °C) temperature stress on young carob seedlings. In stressed plants, mainly the heat-treated, the leaves appear xeromorphic. Parameters of the physiology of the plants such as chlorophyll-a and -b, total phenolic content, and oxidative stress were measured and presented via Principal Component Analysis. Chlorophyll-a and -b contents are inferior in cold-stressed leaves while heat-stressed leaves accumulate more phenolics and experience higher oxidative stress as compared to their cold-stressed counterparts. The phytochemical profile of different extracts obtained from stressed carob leaves was identified so as to gain insight into metabolites produced under stress. Moreover, LC-HRMS/MS metabolomic workflow was utilized for the discovery of biomarkers, over- or under-regulated in stressed conditions. The antimicrobial activity of carob leaf extract fractions was assessed against six human pathogen strains and three phytopathogen bacterial strains. MeOH-H2O and dichloromethane (DCM) extracts presented notable activity against Candida albicans and Saccharomyces cerevisiae, while DCM extracts inhibited the growth of Erwinia amylovora. We may conclude that carob tree exposure to temperature stress does not have a significant influence on secondary metabolic pathways.

Phosphatidic acid signaling in modulating plant reproduction and architecture

Phosphatidic acid (PA) is an important class of signaling lipids involved in various biological processes in plants. Functional characterization of mutants of PA-metabolizing enzymes, combined with lipidomics and protein-lipid interaction analyses, has revealed the key role of PA signaling in plant responses to biotic and abiotic stresses. Moreover, PA and its metabolizing enzymes influence several reproductive processes, including gametogenesis, pollen tube growth, self-incompatibility, haploid embryo formation, embryogenesis, and seed development. They also play a significant role in shaping plant reproductive and root architecture. Recent studies have shed light on the diverse mechanisms of PA's action, though much remains to be elucidated. Here, we summarize recent advances in the study of PA and its metabolizing enzymes, emphasizing their roles in plant sexual reproduction and architecture. We also explore potential mechanisms underlying PA's functions and discuss future research directions.

Odyssey of environmental and microbial interventions in maize crop improvement

Maize (Zea mays) is India's third-largest grain crop, serving as a primary food source for at least 30% of the population and sustaining 900 million impoverished people globally. The growing human population has led to an increasing demand for maize grains. However, maize cultivation faces significant challenges due to a variety of environmental factors, including both biotic and abiotic stresses. Abiotic stresses such as salinity, extreme temperatures, and drought, along with biotic factors like bacterial, fungal, and viral infections, have drastically reduced maize production and grain quality worldwide. The interaction between these stresses is complex; for instance, abiotic stress can heighten a plant's susceptibility to pathogens, while an overabundance of pests can exacerbate the plant's response to environmental stress. Given the complexity of these interactions, comprehensive studies are crucial for understanding how the simultaneous presence of biotic and abiotic stresses affects crop productivity. Despite the importance of this issue, there is a lack of comprehensive data on how these stress combinations impact maize in key agricultural regions. This review focuses on developing abiotic stress-tolerant maize varieties, which will be essential for maintaining crop yields in the future. One promising approach involves the use of Plant Growth-Promoting Rhizobacteria (PGPR), soil bacteria that colonize the rhizosphere and interact with plant tissues. Scientists are increasingly exploring microbial strategies to enhance maize's resistance to both biotic and abiotic stresses. Throughout the cultivation process, insect pests and microorganisms pose significant threats to maize, diminishing both the quantity and quality of the grain. Among the various factors causing maize degradation, insects are the most prevalent, followed by fungal infections. The review also delves into the latest advancements in applying beneficial rhizobacteria across different agroecosystems, highlighting current trends and offering insights into future developments under both normal and stress conditions.

Biochemical, photosynthetic and metabolomics insights of single and combined effects of salinity, heat, cold and drought in Arabidopsis

Ensuring food security is one of the main challenges related to a growing global population under climate change conditions. The increasing soil salinity levels, drought, heatwaves, and late chilling severely threaten crops and often co-occur in field conditions. This work aims to provide deeper insight into the impact of single vs. combined abiotic stresses at the growth, biochemical and photosynthetic levels in Arabidopsis thaliana (L.). Reduced QY max was recorded in salinity-stressed plants, NPQ increased in heat and salinity single and combined stresses, and qP decreased in combined stresses. MDA and H2O2 content were consistently altered under all stress conditions, but higher values were recorded under salinity alone and in combination. Salinity alone and in stress combinations (especially with cold) provided a stronger hierarchical effect. Despite glycine and GABA osmolytes not significantly changing, proline highlighted the hierarchically stronger impact of salinity, while glycine-betaine was decreased under drought combinations. Untargeted metabolomics pointed out distinct metabolic reprogramming triggered by the different stress conditions, alone or in combination. Pathway analysis revealed that abiotic stresses significantly affected hormones, amino acids and derivates, and secondary metabolites. Flavonoids accumulated under drought (alone and combined with heat and cold stresses), while N-containing compounds decreased under all combined stresses. Looking at the interactions across the parameters investigated, antagonistic, additive, or synergistic effects could be observed depending on the biochemical process considered. Notwithstanding, these results contribute to delving into the impact of various stress combinations, hierarchically highlighting the stress-specific effects and pointing out different combinations.

Lipid Profile of Larix cajanderi Mayr in Adaptation to Natural Conditions in the Cryolithozone

The prevalence of coniferous trees in the forest landscapes of northeastern Siberia is conditioned by their high frost resistance. The Kajander larch (Larix cajanderi Mayr), which can survive under natural conditions (down to -60 °C) in the cryolithozone of Yakutia, is the dominant forest-forming species. We hypothesise that our study using HPTLC-UV/Vis/FLD, TLC-GC/FID, and GC-MS methods of seasonal features of the lipid profile of Kajander larch tissues will bring us closer to understanding the mechanisms of participation of lipid components in the adaptation of this valuable tree species to the cold climate of the cryolithozone. Rare delta5-unsaturated polymethylene-interrupted fatty acids (∆5-UPIFA) were identified in the fatty acids (FAs) of L. cajanderi shoots, including 18:2(Δ5.9) (taxoleic), 18:3(Δ5.9.12) (pinolenic), and 18:4(Δ5.9.12.15) (coniferonic). It was found that the content of ∆5-UPIFA in L. cajanderi shoots markedly increased (1.5-fold, representing up to 23.9% of sum FAs) during the autumnal transition of trees to dormancy. It was observed that the ranges of low temperatures experienced during the prolonged winter period primarily determined the structural diversity of membrane lipids and their constituent FAs during the cold adaptation of L. cajanderi. The results obtained can be used for the selection of molecular markers of cold tolerance in woody plants, including fruit trees.

Changes in Metabolites Produced in Wheat Plants Against Water-Deficit Stress

Drought stress can adversely affect the seed germination and seedling growth of wheat plants. This study analyzed the effect of drought on seed germination and the morphological parameters of seedlings from ten winter wheat genotypes. The primary focus was to elucidate the effects of two drought intensities on metabolic status in wheat seedlings. The findings suggest that most wheat genotypes exhibited a significant reduction in germination and growth traits under severe drought, while the genotype Srpanjka exhibited less reduction under both drought conditions. Out of 668 metabolic features, 54 were altered under 10% PEG stress and 140 under 20% PEG stress, with 48 commonly shared between these two stress intensities. This study demonstrated that the metabolic response of shoots to 10% PEG stress contrasts with that of 20% PEG stress. Some growth metabolites, such as oxalic acid, sophorose, and turanose, showed the highest positive increase under both stresses, while butanoic acid, tropic acid, glycine, propionic acid, and phosphonoacetic acid decreased. It is suggested that the accumulation of amino acids, such as proline, contributed to the drought tolerance of the plants. Among all organic acids, succinic and aspartic acids particularly increased the plant response to mild and severe drought stress, respectively. Our results suggest that different metabolites in wheat seedlings enhance the potential ability of wheat to cope with drought stress in the early growth stages by activating a rapid and comprehensive tolerance mechanism. This discovery presents a new approach for enhancing wheat tolerance to abiotic stress, including water deficit.

Impact of Drying on Phytonutritional Compounds, In Vitro Antioxidant Activity and Cytotoxicity of Spiny Saltbush (Rhagodia spinescens)

The Spiny saltbush (Rhagodia spinscens) is a halophyte species with the potential to provide natural ingredients used in food and pharmaceutical industries. In food and pharmaceutical applications, drying is necessary to maintain shelf-life, which reduces phytonutrient content. In this study, changes in the nutritional composition, phenolic and carotenoid profiles of radical antioxidant scavenging activity [(2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)], antioxidant power [ferric reducing antioxidant ability assay (FRAP)], and cytotoxicity of freeze- and oven-dried (55 °C for 24 h) spiny saltbush were determined. Sodium (4.72 g/100 g dry weight (DW), potassium (6.86 g/100 g DW), calcium (4.06 g/100 g DW), zinc (372 mg/kg DW) and protein content were higher in oven-dried samples than freeze-dried samples. Ultra-performance liquid chromatography-mass spectrometry analysis detected 18 metabolites in saltbush extracts. Partial Least-Squares Discriminant Analysis, Hierarchical Cluster Analysis, and Variable Importance in Projection discriminated between freeze-dried and oven-dried samples. Freeze-dried samples retained more individual metabolites than oven-dried samples, while oven-dried samples had higher antioxidant activity (ABTS and FRAP), lutein, trans-β carotene, and cis-β-carotene. Correlation analysis identified potential antioxidant candidates between phenolic and carotenoid compounds. Neither freeze-dried nor oven-dried spiny saltbush samples showed cytotoxicity. The study uncovered changes in phytonutritional compounds after the oven and freeze-drying spiny saltbush, a potential salt alternative and functional ingredient for the food industry.

Effects of water deficit on two cultivars of Hibiscus mutabilis: A comprehensive study on morphological, physiological, and metabolic responses

Hibiscus mutabilis, commonly known as the cotton rose, is a widely cultivated ornamental and has been acclaimed as the representative flower of the 2024 World Horticultural Exposition. The growth and ornamental characteristics of Hibiscus mutabilis can be affected by drought stress. Therefore, we investigated the physiological and metabolic responses of drought-sensitive Hibiscus mutabilis JRX-1 and drought-tolerant Hibiscus mutabilis CDS-4 under drought stress. The results of the physiological analyses revealed that, compared to JRX-1,CDS-4 maintained good growth and greater water use efficiency through stronger antioxidant defences, osmoregulatory capacity and stomatal regulation. A total of 3277 metabolites were identified in positive and negative ion modes, of which 663 metabolites presented changes in expression under drought conditions, including 306 upregulated metabolites and 357 downregulated metabolites. Secondary metabolites, such as flavonoids and diterpenoids, are crucial in the plant response to drought stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the differentially aboundant metabolites were significantly enriched in the pathways valine, leucine and isoleucine degradation; linoleic acid metabolism; one carbon pool by folate; and folate biosynthesis. The results of this study will not only help to elucidate and apply the physiological and metabolic regulatory strategies of Hibiscus mutabilis to improve its adaptation to water deficit conditions, but will also provide valuable guidance to breeders and molecular biologists in the screening and use of drought resistant genes in ornamental plants.

Development and drought escape response in Arabidopsis thaliana are regulated by AtPLC1 in response to abscisic acid

MAIN CONCLUSION

AtPLC1 plays a critical role in plant growth, development, and response to drought stress. Phosphoinositide-specific phospholipase C (PI-PLC) hydrolyzes substrates to generate secondary messengers crucial for plant growth, development, and stress responses. Drought escape (DE) response is an adaptive strategy that plants employ under drought conditions. The expression levels of the flower meristem-specific gene APETALA 1 and flowering regulatory genes FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 were downregulated in plc1, and FLOWERING LOCUS C was upregulated. The flowering time of the plc1flc double mutant was earlier than that of the wild type. Transcriptome analysis revealed that the Gene Ontology of differentially expressed genes (DEGs) was enriched in abscisic acid (ABA) response signaling, and Kyoto Encyclopedia of Genes and Genomes analysis revealed differential gene expression annotated to plant hormone signaling pathways. Our experiments show that AtPLC1 is upregulated by ABA in Arabidopsis. Under ABA induction and water stress, wild-type plants exhibit a DE response, and the DE response in plc1 disappears. Expression levels of ABA signaling pathway transcription factors ABA-responsive element-binding factors 3 (ABF3) and ABF4 were downregulated in plc1. In conclusion, our study suggests that AtPLC1 participates in regulating plant growth and development and participates in the DE response through the regulation of ABA signaling pathway transcription factors ABF3/ABF4. The study enhances our comprehension of the role of AtPLC1 in plant development and drought stress, providing a theoretical foundation for further investigation into DE responses.

Multifaceted natural drought response mechanisms in three elite date palm cultivars uncovered by expressed sequence tags analysis

This study extends our prior research on drought responses in three date palm cultivars (Khalas, Reziz, and Sheshi) under controlled conditions. Here, we investigated their drought stress adaptive strategies under ambient environment. Under natural field drought conditions, three date palm cultivars experienced significantly (p ≤ 0.05) varying regulations in their physiological attributes. Specifically, chlorophyll content, leaf RWC, photosynthesis, stomatal conductance, and transpiration reduced significantly, while intercellular CO2 concentration and water use efficiency increased. Through suppression subtraction hybridization (SSH), a rich repertoire (1026) of drought-responsive expressed sequence tags (ESTs) were identified: 300 in Khalas, 343 in Reziz, and 383 in Sheshi. Functional analysis of ESTs, including gene annotation and KEGG pathways elucidation, unveiled that these cultivars withstand drought by leveraging indigenous and multifaceted pathways. While some pathways aligned with previously reported drought resilience mechanism observed under controlled conditions, several new indigenous pathways were noted, pinpointing cultivar-specific adaptations. ESTs identified in three date palm cultivars were enriched through GSEA analysis. Khalas exhibited enrichment in cellular and metabolic processes, catalytic activity, and metal ion binding. Reziz showed enrichment in biological regulation, metabolic processes, signaling, and nuclear functions. Conversely, Sheshi displayed enrichment in organelle, photosynthetic, and ribosomal components. Notably, ca. 50% of the ESTs were unique and novel, underlining the complexity of their adaptive genetic toolkit. Overall, Khalas displayed superior drought tolerance, followed by Reziz and Sheshi, highlighting cultivar-specific variability in adaptation. Conclusively, date palm cultivars exhibited diverse genetic and physiological strategies to cope with drought, demonstrating greater complexity in their resilience compared to controlled settings.

Exploring lipid signaling in plant physiology: From cellular membranes to environmental adaptation

Lipids have evolved as versatile signaling molecules that regulate a variety of physiological processes in plants. Convincing evidence highlights their critical role as mediators in a wide range of plant processes required for survival, growth, development, and responses to environmental conditions such as water availability, temperature changes, salt, pests, and diseases. Understanding lipid signaling as a critical process has helped us expand our understanding of plant biology by explaining how plants sense and respond to environmental cues. Lipid signaling pathways constitute a complex network of lipids, enzymes, and receptors that coordinate important cellular responses and stressing plant biology's changing and adaptable traits. Plant lipid signaling involves a wide range of lipid classes, including phospholipids, sphingolipids, oxylipins, and sterols, each of which contributes differently to cellular communication and control. These lipids function not only as structural components, but also as bioactive molecules that transfer signals. The mechanisms entail the production of lipid mediators and their detection by particular receptors, which frequently trigger downstream cascades that affect gene expression, cellular functions, and overall plant growth. This review looks into lipid signaling in plant physiology, giving an in-depth look and emphasizing its critical function as a master regulator of vital activities.

Biological Nano-Agrochemicals for Crop Production as an Emerging Way to Address Heat and Associated Stresses

Climate change is a global problem facing all aspects of the agricultural sector. Heat stress due to increasing atmospheric temperature is one of the most common climate change impacts on agriculture. Heat stress has direct effects on crop production, along with indirect effects through associated problems such as drought, salinity, and pathogenic stresses. Approaches reported to be effective to mitigate heat stress include nano-management. Nano-agrochemicals such as nanofertilizers and nanopesticides are emerging approaches that have shown promise against heat stress, particularly biogenic nano-sources. Nanomaterials are favorable for crop production due to their low toxicity and eco-friendly action. This review focuses on the different stresses associated with heat stress and their impacts on crop production. Nano-management of crops under heat stress, including the application of biogenic nanofertilizers and nanopesticides, are discussed. The potential and limitations of these biogenic nano-agrochemicals are reviewed. Potential nanotoxicity problems need more investigation at the local, national, and global levels, as well as additional studies into biogenic nano-agrochemicals and their effects on soil, plant, and microbial properties and processes.

Transcriptomic Analyses Reveal That Coffea arabica and Coffea canephora Have More Complex Responses under Combined Heat and Drought than under Individual Stressors

Increasing exposure to unfavorable temperatures and water deficit imposes major constraints on most crops worldwide. Despite several studies regarding coffee responses to abiotic stresses, transcriptome modulation due to simultaneous stresses remains poorly understood. This study unravels transcriptomic responses under the combined action of drought and temperature in leaves from the two most traded species: Coffea canephora cv. Conilon Clone 153 (CL153) and C. arabica cv. Icatu. Substantial transcriptomic changes were found, especially in response to the combination of stresses that cannot be explained by an additive effect. A large number of genes were involved in stress responses, with photosynthesis and other physiologically related genes usually being negatively affected. In both genotypes, genes encoding for protective proteins, such as dehydrins and heat shock proteins, were positively regulated. Transcription factors (TFs), including MADS-box genes, were down-regulated, although responses were genotype-dependent. In contrast to Icatu, only a few drought- and heat-responsive DEGs were recorded in CL153, which also reacted more significantly in terms of the number of DEGs and enriched GO terms, suggesting a high ability to cope with stresses. This research provides novel insights into the molecular mechanisms underlying leaf Coffea responses to drought and heat, revealing their influence on gene expression.

Comparing the Mechanical Properties of Rice Cells and Protoplasts under PEG6000 Drought Stress Using Double Resonator Piezoelectric Cytometry

Plant cells' ability to withstand abiotic stress is strongly linked to modifications in their mechanical characteristics. Nevertheless, the lack of a workable method for consistently tracking plant cells' mechanical properties severely restricts our comprehension of the mechanical alterations in plant cells under stress. In this study, we used the Double Resonator Piezoelectric Cytometry (DRPC) method to dynamically and non-invasively track changes in the surface stress (ΔS) generated and viscoelasticity (storage modulus G' and loss modulus G″) of protoplasts and suspension cells of rice under a drought stress of 5-25% PEG6000. The findings demonstrate that rice suspension cells and protoplasts react mechanically differently to 5-15% PEG6000 stress, implying distinct resistance mechanisms. However, neither of them can withstand 25% PEG6000 stress; they respond mechanically similarly to 25% PEG6000 stress. The results of DRPC are further corroborated by the morphological alterations of rice cells and protoplasts observed under an optical microscope. To sum up, the DRPC technique functions as a precise cellular mechanical sensor and offers novel research tools for the evaluation of plant cell adversity and differentiating between the mechanical reactions of cells and protoplasts under abiotic stress.

Exploring the Role of TaPLC1-2B in Heat Tolerance at Seedling and Adult Stages of Wheat through Transcriptome Analysis

Heat stress is a major abiotic stress that can cause serious losses of a crop. Our previous work identified a gene involved in heat stress tolerance in wheat, TaPLC1-2B. To further investigate its mechanisms, in the present study, TaPLC1-2B RNAi-silenced transgenic wheat and the wild type were comparatively analyzed at both the seedling and adult stages, with or without heat stress, using transcriptome sequencing. A total of 15,549 differentially expressed genes (DEGs) were identified at the adult stage and 20,535 DEGs were detected at the seedling stage. After heat stress, an enrichment of pathways such as phytohormones and mitogen-activated protein kinase signaling was mainly found in the seedling stage, and pathways related to metabolism, glycerophospholipid metabolism, circadian rhythms, and ABC transporter were enriched in the adult stage. Auxin and abscisic acid were downregulated in the seedling stage and vice versa in the adult stage; and the MYB, WRKY, and no apical meristem gene families were downregulated in the seedling stage in response to heat stress and upregulated in the adult stage in response to heat stress. This study deepens our understanding of the mechanisms of TaPLC1-2B in regard to heat stress in wheat at the seedling and adult stages.