Drought is an important abiotic factor constricting crop production globally. Although the role of JAZ proteins in regulating jasmonic acid signaling and plant responses to environmental stress is well documented, their specific functions and underlying mechanisms in plants remains little known. In this study, JAZ proteins in barley were thoroughly analyzed, revealing a total of 11 members classified into three phylogenetic subgroups. HvJAZ2, based on its distinct expression patterns, is considered as a key candidate gene for regulating drought tolerance in barley. Using the HvJAZ2 knockout mutants, we revealed that the gene negatively regulates drought tolerance by inhibiting barley root growth. Notably, the jaz2 mutants up-regulated expression of root development genes, including SHR1, PLT1, PLT2, and PLT6. plt2 and plt1/plt2 mutants exhibited suppressed root development and reduced drought tolerance. Analysis of interactions between HvJAZ2 and other proteins showed that HvJAZ2 is not directly interacted with HvPLT1/2/6, but interacts with some other proteins. BIFC and LCA assays further confirmed the nuclear interaction between HvJAZ2 and HvMYC2. Y1H and Dual-Luciferase experiments demonstrated that HvMYC2 can bind to and activates the HvPLT2 promoter. In summary, HvJAZ2 negatively regulates root development and drought tolerance in barley by suppressing HvPLT2 expression through interacting with HvMYC2.

The impact of nitrogen (N) and phosphorus (P) on the physiological and biochemical processes crucial for tree seedling growth is substantial. Although the study of plant hydraulic traits in response to N and P is growing, comprehensive research on their combined effects remains limited. Malus sieversii, a key ancestral species of modern apples and a dominant species in Xinjiang’s Tianshan wild fruit forest, is witnessing a decline due to climate change, pests and diseases, compounded by challenges in seedling regeneration. Addressing this, a four-year study was conducted to determine the optimal fertilization method for it. The experiment explored varying levels of N (N10, N20, N40) and P (P2, P4, P8), and their combined effects (N20Px: N20P2, N20P4, N20P8; NxP4: N10P4, N20P4, N40P4), assessing their impact on gas exchange, hydraulic traits, and the interplay among functional traits in Tianshan Mountains’ M. sieversii seedlings. Our study revealed that all nitrogen treatments enhanced gas exchange, while phosphorus addition negatively impacted it. N10 significantly increasing leaf hydraulic conductivity. All phosphorus-inclusive fertilizers adversely affected hydraulic conductivity. P8, N20P4 and N20P8 notably increased seedlings’ vulnerability to embolism. Seedlings can adaptively adjust multiple functional traits in response to nutrient changes. The research suggests N10 and N20 as the most effective fertilization treatments for M. sieversii seedlings in this region, while fertilization involving phosphorus is less suitable. This study contributes valuable insights into the specific nutrient needs of it, vital for conservation and cultivation efforts in the Tianshan region.

To avoid reaching lethal temperatures during periods of heat stress, plants may acclimate either their biochemical thermal tolerance, or leaf morphological and physiological characteristics to reduce leaf temperature (T leaf). While emerging evidence indicates that plants from warmer environments have a greater capacity to regulate T leaf, the extent of intraspecific variation and contribution of provenance is relatively unexplored. We tested whether upland and lowland provenances of four tropical tree species grown in a common garden differed in their thermal safety margins by measuring leaf thermal traits, midday leaf-to-air temperature differences (∆T leaf), and critical leaf temperature defined by chlorophyll fluorescence (T­ crit). Provenance variation was highly species- and trait- specific. Higher ∆T leaf and T­ crit were observed in the lowland provenance for Terminalia microcarpa, and in the upland provenance for Castanospermum australe, with no provenance differences observed in the other two species. Within-species covariation of T crit and ∆T leaf led to a convergence of thermal safety margins across provenances. These findings suggest that when grown under common conditions, lowland and upland provenances may not differ substantially in their vulnerability (defined here as thermal safety margin) to heat stress, despite differences in operating temperatures and T crit.

The massive leaf shedding in monoculture soybeans post-anthesis detrimentally impacts production, whereas relay strip intercropping can extend leaf area duration to enhance overall productivity. To reveal the reasons for leaf shedding in monoculture soybeans and how it affects the physiological and biochemical functions of source and sink organs, we conducted a four-year field experiment and a leaf-removal simulation experiment in relay strip intercropped soybeans to measure the phenotypic and physiological traits of leaves and nodules. The results showed that the strong self-shading of leaves in monoculture soybeans led to extensive defoliation, while the superior light environment in relay strip intercropped soybeans can promote the maintenance of a higher leaf area, nodule growth, and photosynthetic carbon allocation. With increasing leaf removal, leaf growth increased first and then decreased, and leaf defoliation gradually decreased. Extensive leaf-removal reduced Rubisco activity and sucrose phosphate synthase (SPS) activity in leaves, as well as the content of sucrose, malate, ATP, and energy charge (EC) in nodules, with a trade-off between leaf mass enhancement and weakened nodule growth. Notably, moderate leaf-removal could balance compensation and consumption. The total non-structural carbohydrates (TNC) in roots, N and Ureide in leaves and pods increased in unison, achieving the synergies between leaves and nodules to maintain a higher energy status and growth rate. Our study highlights that the favorable light environment in relay strip intercropping system shapes the coordinated functioning of above-ground and below-ground source-sink organs and effectively promoting photosynthesis and nitrogen fixation. These findings contribute to a better understanding of the underlying mechanisms of effective resource utilization in different cropping patterns, aiding in the sustainable development of food production.

Climate change is leading to more frequent and severe extreme temperature events, negatively impacting agricultural productivity and threatening global food security. Plant reproduction, the process underpinning crop yield, is highly susceptible to heatwaves, affecting pollen development and ultimately affecting seed set and crop yields. Recent research has increasingly focused on understanding how pollen grains from various crops react to heat stress at the molecular and cellular levels. This surge in interest over the last decade has been underpinned by advances in genomic technologies, such as single-cell RNA sequencing, which holds significant potential for revealing the underlying regulatory reprogramming triggered by heat stress throughout the various stages of pollen development. This review focuses on how heat stress affects gene regulatory networks, including the heat stress response, the unfolded protein response, and autophagy, and discusses the impact of these changes on various stages of pollen development. It highlights the potential of pollen selection as a key strategy for improving heat tolerance in crops by leveraging the genetic variability among pollen grains. Additionally, genome-wide association studies and population screenings have shed light on the genetic underpinnings of traits in major crops that respond to high temperatures during male reproductive stages. Moreover, gene-editing tools like CRISPR/Cas systems could facilitate precise genetic modifications to boost pollen heat resilience. The information covered in this review is valuable for selecting traits and employing molecular genetic approaches to develop heat-tolerant genotypes.

A key challenge in molecular breeding is breaking trait coupling. Recently, Zhang et al. found inhibiting tissue-specific BR pathway expression in rice increases panicle number by over 40% without affecting grain size, offering a strategy to avoid hormonal negative effects by optimizing hormone spatial distribution.

Endoplasmic Reticulum-Plasma Membrane contact sites (ER-PM CS) are evolutionarily conserved membrane domains found in all eukaryotes, where the endoplasmic reticulum (ER) closely interfaces with the plasma membrane (PM). This short distance is achieved in plants through the action of tether proteins such as Synaptotagmins (SYTs). Arabidopsis comprises five SYT members ( SYT1-SYT5), but whether they possess overlapping or distinct biological functions remains elusive. SYT1, the best-characterized member, plays essential roles in the resistance to abiotic stress. This study reveals that the functionally redundant SYT1 and SYT3 genes, but not SYT5, are involved in salt and cold stress resistance. We also show that, unlike SYT5, SYT1 and SYT3 are not required for Pseudomonas syringae resistance . Since SYT1 and SYT5 interact in vivo via their SMP domains , the distinct functions of these proteins cannot be caused by differences in their localization. Interestingly, structural phylogenetic analysis indicates that SYT1 and SYT5 clades emerged early in the evolution of land plants. We also show that SYT1 and SYT5 clades exhibit different structural features, rationalizing their distinct biological roles.

The increased production and use of plastics have negative impacts on the environment. However, not only the polymers themselves, but also smaller particles used for instance in cosmetics or derived from decomposition are toxicologically relevant. In recent years, research has focused on the occurrence of micro- and nanoplastics (MNPs) in air, soil and water, whereas the entry into plants has hardly been investigated. To determine the load, translocation of MNPs and their effects on metabolism, pak choi, tomato, radish and asparagus have been exposed with fluorescent-labeled particles; poly(methyl methacrylate) (PMMA) or polystyrene (PS) of different sizes and surface modifications. By means of fluorescence microscopy the entry of NP regardless of their size (100 nm – 500 nm) and surface modification (unmodified, COOH or NH 2) has been demonstrated. Additionally, metabolic changes induced by MNPs have been determined by metabolomics. The entry could pose a potential risk to food safety as well as quality and needs greater concern and further research.

In Chlamydomonas, the directly light-gated, plasma membrane-localized (PM) cation channels channelrhodopsins ChR1 and ChR2 are the primary photoreceptors for phototaxis. Their targeting and abundance is essential for optimal movement responses. However, our knowledge how Chlamydomonas achieves this is still at its infancy. Here we show that ChR1 internalization occurs via light-stimulated endocytosis. Prior or during endocytosis ChR1 is modified and forms high molecular mass complexes. These are the solely detectable ChR1 forms in extracellular vesicles (EVs) and their abundance therein dynamically changes upon illumination. The ChR1-containing EVs are secreted via the PM and/or the ciliary base. In line with this, ciliogenesis mutants exhibit increased ChR1 degradation rates. Further, we establish involvement of two cysteine proteases in its turnover: CEP1, a papain-type C1A member, and a calpain. ΔCEP1 knock-out strains lack light-induced ChR1 degradation, whereas ChR2 degradation was unaffected. Low light stimulates CEP1 expression, which is regulated via phototropin, a SPA1 E3 ubiquitin ligase and cAMP. Further, mutant and inhibitor analyses revealed involvement of the small GTPase ARL11 and SUMOylation in ChR1 targeting to the eyespot and cilia. Our study thus defines the degradation pathway of this central photoreceptor of Chlamydomonas and identifies novel elements involved in its homeostasis and targeting.

Tree transpiration dynamics and mechanisms in karst habitats are not fully understood due to the heterogeneous environmental features and complex species composition. Two common coexisting tree species, Mallotus philippensis and Celtis biondii, were examined in soil- and rock-dominated (SD and RD) karst habitats. Soil moisture, plant transpiration, root distribution, and leaf water potential were measured over two years (2021 and 2022). The mean water content was significantly lower in the RD than in the SD habitat. Transpiration patterns also differed between habitats, although species-specific distinctions were driven by leaf and root physiological traits. M. philippensis showed an isohydric tendency in both habitats and a lower density of fine roots, mostly in the soil zone, in the RD habitat. The transpiration of M. philippensis followed the variation in soil moisture, being lower in the RD habitat. Conversely, an anisohydric tendency in both habitats and a higher density of fine roots in both the soil and bedrock zones in the RD habitat were found in C. biondii. This species showed higher transpiration in the RD habitat, arising from ample water availability from soil and epikarst. Our findings reveal the regulatory mechanisms of species-specific root-zone water availability in transpiration patterns across karst habitats.

The root cortex is an important anatomical phenes, and root cortical senescence (RCS) is closely associated with root absorptive function. However, characteristics and responses of RCS to drought stress in cotton have received little attention. This study subjected the drought-tolerant cotton variety “Guoxin 02” and the drought-sensitive variety “Ji 228” to drought stress (8% PEF6000) and no-stress (0% PEG6000) treatments to determine the characteristics and responses of cotton RCS to drought stress. The results showed that the RCS of the two varieties was significantly promoted under drought stress. The greater the distance from the root tip, the more severe the RCS occurrence under drought stress compared with non-stress treatment. The occurrence of RCS in “Guoxin 02” highered by 14.03%-20.18% compared to “Ji 228” under drought stress. Moreover, the RCS was significantly negatively correlated with root respiration but significantly positively correlated with total root length and leaf water potential ( p < 0.05). Indole-3-acetic acid (IAA) content increased, while abscisic acid (ABA) content decreased as the RCS increased. In summary, endogenous hormones regulated the occurrence of RCS, which reduced the root metabolic costs and seemingly achieved more resource redistribution to new roots, thereby expanding the water absorption capacity of roots to fully utilize deep water resources. Thus, the study demonstrates the potential of RCS in improving the drought stress tolerance of cotton.

Allotetraploid white clover formed during the last glaciation through hybridisation of two European diploid progenitors from restricted niches: one coastal, the other alpine. Here, we examine which hybridisation-derived molecular events may have underpinned white clover’s post-glacial niche expansion. We compared the transcriptomic frost responses of white clovers (inbred line and an alpine-adapted ecotype), extant descendants of its progenitor species and a resynthesised white clover neopolyploid to identify genes that were exclusively frost-induced in the alpine progenitor and its derived subgenomes. From these analyses we identified galactinol synthase, the rate-limiting enzyme in biosynthesis of the cryoprotectant raffinose, and found that the extant descendants of the alpine progenitor as well as the neopolyploid white clover rapidly accumulated significantly more galactinol and raffinose than the coastal progenitor under cold stress. The frost-induced galactinol synthase expression and rapid raffinose accumulation derived from the alpine progenitor likely provided an advantage during early post-glacial colonisation for white clover compared to its coastal progenitor.

Early sowing can help summer crops escape drought and can mitigate the impacts of climate change on them, but it exposes them to cold stress during initial developmental stages, which has both immediate and long-term effects on development and physiology. To understand how early night-chilling stress impacts plant development and the yield, we studied the reference sunflower line XRQ under controlled, semi-controlled and field conditions. We performed high-throughput imaging of the whole plant parts and obtained physiological and transcriptomic data from leaves, hypocotyls and roots. We observed morphological reductions in early stages under field and controlled conditions, with a decrease in root development, an increase in reactive oxygen species content in leaves and changes in lipid composition in hypocotyls. A long-term increase in leaf chlorophyll suggests a stress memory mechanism that was supported by transcriptomic induction of histone coding genes. We highlighted leaf transcriptomes in cold-acclimation genes such as chaperone, heat shock and late embryogenesis abundant proteins. We identified genes in hypocotyls involved in lipid, cutin, suberin and phenylalanine ammonia lyase biosynthesis and ROS scavenging. This comprehensive study describes new phenotyping methods and candidate genes to understand phenotypic plasticity better in response to chilling and study stress memory in sunflower.

Mesophyll conductance ( g m ) describes the efficiency with which CO 2 moves from substomatal cavities to chloroplasts. Despite the stipulated importance of leaf architecture in affecting g m , there remains a considerable ambiguity about how and whether anatomy influences g m . This is, in part, because studies exploring the relationship between leaf architecture and g m have often relied on simple linear or exponential models to identify correlations. Here, we employed non-linear machine learning models to more comprehensively assess the relationship between ten leaf architecture traits and g m . These models achieved excellent predictability of g m , which depended on the leaf architecture traits considered as predictors. Dissection of the importance of leaf architecture traits in the models indicated that cell wall thickness and chloroplast area exposed to internal airspace have a large impact on interspecific variation in g m . Additionally, other leaf architecture traits, such as: leaf thickness, leaf density, and chloroplast thickness emerged as important predictors of g m . We found significant differences in the predictability between models trained on different plant functional types (PFTs): those trained on woody species could predict g m by anatomical traits on other woody PFTs, ferns, and C 3 herbaceous plants, whereas the converse did not hold in general. By moving beyond simple linear and exponential models, our analyses demonstrated that a larger suite of leaf architecture traits drive differences in g m than has been previously acknowledged. These findings pave the way for modulating g m by strategies that modify its leaf architecture determinants.

Changes in leaf temperature are known to drive stomatal responses, because the leaf-to-air water vapor gradient (Δ w) increases with temperature if ambient vapor pressure is held constant, and stomata respond to changes in Δ w. However, the direct response of stomata to temperature (DRST; the response when Δ w is held constant by adjusting ambient humidity) has been examined far less extensively. Though the meager available data suggest the response is usually positive, results differ widely and defy broad generalization. As a result, little is known about the DRST. This review discusses the current state of knowledge about the DRST, including numerous hypothesized biophysical mechanisms, potential implications of the response for plant adaptation, and possible impacts of the DRST on plant-atmosphere carbon and water exchange in a changing climate.

Gummy stem blight (GSB), a severe and widespread disease causing great losses to cucurbit production, is a major threat to melon production. However, the melon-GSB interaction remains largely unknown, which significantly impedes the genetic improvement of melon for GSB resistance. Here, full-length transcriptome and widely targeted metabolome were used to reveal the early defense responses of resistant (PI511890) and susceptible (Payzawat) melon to GSB. Differentially expressed genes were specifically enriched in the secondary metabolite biosynthesis and MAPK signaling pathway in PI511890, while in carbohydrate metabolism and amino acid metabolism in Payzawat. More than 1000 novel genes were identified in PI511890, which were enriched in the MAPK signaling pathway. There were 11,793 alternative splicing events identified and involved the defense response to GSB. A total of 910 metabolites were identified, with flavonoids as the dominant metabolites. Integrated full-length transcriptome and metabolome analysis showed that eriodictyol and oxalic acid may be used as marker metabolites for GSB resistance in melon. Moreover, post-transcription regulation was widely involved in the defense response of melon to GSB. These results improve our understanding of the interaction between melon and GSB and may facilitate the genetic improvement of GSB resistance of melon.

Illuminated leaves assimilate CO 2 via gross photosynthesis and liberate CO 2 via photorespiration and ‘day respiration’, often denoted as R d. Day respiration is a minor CO 2-exchange component of net photosynthesis but is important for carbon use efficiency, computations of internal conductance, or the interpretation of net photosynthetic 12C/ 13C fractionation. Unfortunately, there is no simple method to measure R d and tracing the origin of C-atoms found in day-respired CO 2 is difficult. As a result, a common misconception is that day respiration is simply a catabolic, CO 2-producing flux through ordinary catabolism (glycolysis and Krebs ‘cycle’). In the past few years, considerable progress has been made in our understanding of day respiration. It appears that R d is a net flux resulting from several CO 2-generating and CO 2-fixing reactions, not only related to catabolism but also to anabolism (biosyntheses). In addition, there is now direct evidence that decarboxylating reactions are partly fed by carbon sources disconnected from current photosynthesis and this effect has consequences for isotopic mass-balance. Therefore, leaf day ‘respiration’ is much more than just CO 2 production by respiratory catabolism. Rather, it reflects whole metabolic orchestration of leaves from N fixation to secondary metabolism and it perhaps deserves another name, such as “day decarboxylations”.

While dynamic regulation of photosynthesis in fluctuating light is increasingly recognized as an important driver of carbon uptake, acclimation to realistic patterns of light fluctuations is still largely unexplored. We subjected Arabidopsis thaliana (L.) plants to light fluctuations with distinct amplitudes and average irradiance. Using gas-exchange and thermal imaging, we examined how light fluctuations affected leaf structure, photosynthetic capacity, and water relations. We found a wider amplitude of fluctuations produced a stronger acclimation response. Large reductions of leaf mass per area under fluctuating light framed our interpretation of changes in pigment content and photosynthetic capacity, in that photosynthetic investment increased markedly on a mass basis, but only a little on an area basis. Moreover, leaf transpiration rose sharply, being nearly four times under fluctuating light. Our findings indicate that leaves growing under fluctuating light, although thinner, maintained their photosynthetic capacity; suggesting their photosynthesis may be more cost-efficient than those under steady light, but overall may incur increased maintenance costs. This is especially relevant for plant performance globally, because naturally fluctuating light created conflicting acclimation cues for photosynthesis and transpiration that may hinder progress towards ensuring food security under climate-related extremes of water stress.