Journal of Experimental Botany

All living organisms rely on the movement of ions across cell membranes as the fundamental physical basis of their internal energy and signaling, and plants are no exception. Plants perceive, integrate, and respond to environmental stimuli through electrical signals, classified as action, variation, and system potentials, that are coupled with calcium waves, reactive oxygen species, and hydraulic and hormonal changes to coordinate whole-organism responses despite the absence of a nervous system. Yet most studies characterize these signals using a single feature, such as amplitude or spike duration, in a single tissue, an approach that cannot establish how such signals correspond to the underlying ionic activity, mobility, and structural complexity of the signaling environment, or how this correspondence varies across organs. Here, we correlate plant bioelectrical signals with potential ionic energy flow using a multi-domain framework, combining discrete spike events, continuous waveform properties, spectral composition, and signal complexity applied to leaf, stem, and root recordings from tomato (Solanum lycopersicum) exposed to different stimulus. Electrical activity with increased stimulus strength, likely reflecting increased ionic flow, with the root showing the largest response. This suggests plant electrical signaling works as a distributed, ion-based information system, useful for stress monitoring and bio-inspired sensor design.

Starch granule initiation involves the extension of maltooligosaccharide primers by glucosyltransferases. STARCH SYNTHASE 4 (SS4) plays a central role in almost all examined plant species, while the plastidial PHOSPHORYLASE 1 (Pho1) also plays an important role in some species, including rice and wheat. In Arabidopsis, an additional enzymatically inactive homolog of SS4, STARCH SYNTHASE 5 (SS5) contributes to starch granule initiation. To elucidate the mechanism of starch granule initiation in potato tubers, we used CRISPR/Cas9 to generate ss4, ss5, and pho1a knockout mutants in the commercial tetraploid 'Clearwater Russet', to systematically investigate their contribution to granule initiation. In ss4 and ss5 tubers, starch granule size and morphology were unaltered relative to the wild type, suggesting that SS4 and SS5 are dispensable for normal granule initiation in potato tubers. In contrast, pho1a tubers had compound starch granules that arose from multiple initiations, greatly reduced granule size, and highly variable granule morphologies. Affinity pull-down to find Pho1a interaction partners identified LIKE EARLY STARVATION (LESV), although yeast 2-hybrid assays did not show direct protein-protein binding. When expressed alone in Nicotiana benthamiana leaves, Pho1a located to the chloroplast stroma, but when expressed alongside LESV, both proteins co-located on starch granules. This co-localisation, alongside the similar accumulation of small starch granules when LESV is knocked out in tubers, suggest a possible functional interaction in planta. These findings position Pho1a as the central glucosyltransferase in starch granule initiation in Clearwater Russet tubers, where it acts together with LESV.

Plant encounters with saline conditions trigger a phase of osmotic stress, followed by ionic stress as salt accumulates in plant tissue. Jasmonate (JA) signalling plays a vital role in both phases, but its role for adaptation depends on timing. Using wild-type rice (Oryza sativa L. cv. Kitaake) and a JA-deficient allene oxide cyclase (aoc) mutant, we followed whole-plant physiology (growth, biomass, photosynthesis, ion distribution) with expression analysis for genes of jasmonate signalling, ion transporters and redox balance to separate adaptive from maladaptive JA effects. The aoc mutant sustained shoot and root growth more effectively than the wild type, maintaining cell expansion in the shoot and cell proliferation in the root under saline conditions. Likewise, stomatal conductance in the mutant was more persistent under salinity, accompanied by improved shoot K/Na homeostasis and reduced sodium in young leaves. In the wild-type, prolonged saline conditions were linked with induction of OsJAZ13 and OsNHX1, stomatal closure and chlorophyll degradation. We discuss these findings in the context of a model, where the function of JA signalling does not merely depend on its accumulation, but on its temporal dynamics. Here, OsHAK16 emerges as a marker of early adaptive responses, whereas OsNHX1 and OsJAZ13 characterize later maladaptive stress states, emphasising the potential of modulating JA dynamics to improve salt resilience in rice breeding.

Slow stomatal opening after increases in irradiance constrains carbon gain under fluctuating light, yet stomatal kinetics remain an underexplored target for crop improvement. Here, we investigated Oryza sativa PROTON ATPASE TRANSLOCATION CONTROL 1 (OsPATROL1), which encodes a Munc13-like protein implicated in stomatal regulation in Arabidopsis thaliana. OsPATROL1 overexpression had modest, condition-dependent effects on steady-state gas exchange and did not alter stomatal morphology or biochemical traits. In contrast, it consistently accelerated stomatal opening and photosynthetic induction, reducing the stomatal conductance time constant during induction by 41-43%. During 12 h of simulated natural fluctuating light, OsPATROL1-overexpressing plants maintained higher stomatal conductance and net CO2 assimilation rate, increasing cumulative assimilation by 8-12% while maintaining their intrinsic water-use efficiency (iWUE). Under artificial fluctuating light, overexpression alleviated growth reductions relative to steady light. Under glasshouse conditions, total biomass increased by 34-44%, accompanied by greater tiller number, root biomass, bleeding sap rate, and leaf nitrogen content. Taken together, these results indicate that OsPATROL1 overexpression accelerates stomatal opening, enhances photosynthetic induction and daytime carbon gain without compromising iWUE, and is associated with greater growth.

Gene regulatory networks (GRNs) establish the spatio-temporal gene expression patterns necessary for reproducible development of organisms. MicroRNAs have emerged as important regulators of gene expression controlling either target gene levels, spatial patterns or timing. These molecular functions may vary depending on how they are integrated into GRNs. Here we used the Arabidopsis leaf as a model to study the genetic and molecular interactions between the CUP-SHAPED COTYLEDON 2 (CUC2) transcription factor and its negative regulator, miR164A. Quantitative morphometric analyses showed that miR164A acts from early stages during leaf development regulating CUC2 expression dynamic rather than the spatial distribution of CUC2. At the molecular level, CUC2 directly activates MIR164A expression, forming a single negative feedback loop. Further, using a ratiometric approach, we identified a cis-regulatory element (CRE) sufficient to drive CUC2-dependent MIR164A expression at the leaf sinus. Ordinary differential equation (ODE) modelling suggests that CUC2-CRE may control the timely accumulation of CUC2. Accordingly, quantification of CUC2 protein accumulation dynamics using a spatio-temporal mean cartography strategy in CRISPR cis-regulatory variants at the MIR164A locus revealed that CUC2-dependent MIRA164A expression is required to maintain both the precise timing of CUC2 expression and CUC2 levels. Altogether, our work provides experimental evidence for a specific role of the CUC2-MIR164A module in shaping leaf development, highlighting the contribution of network topology to GRN functions.

Shoot branching is a highly plastic developmental process that allows plants to adjust their architecture to environmental conditions, such as carbon and nitrogen availability. Although the class II TCP transcription factor BRANCHED1 is a well-established repressor of shoot branching, the contribution of other TCP factors during this process remains less well understood. Here, we show that the miR319-targeted TCP module promotes shoot branching in Arabidopsis thaliana. Overexpression of miR319 reduced rosette branch production, whereas repression of TCP3 activity or triple knockout (KO) mutation in TCP3, TCP4 and TCP10 inhibited branching. Conversely, expression of a miR319-resistant TCP3 triggered a highly branched phenotype, indicating that TCP3 and related miR319 targets act as positive regulators of shoot branching. Genetic analysis with the strigolactone-deficient max4 mutant showed that strigolactones mediate, at least partly, the reduced branching observed in the miR319 overexpressing line and in the tcp3,4,10 triple mutant. Transcriptomic and DNA-binding analyses indicated indirect effect of TCP3 on strigolactone biosynthesis genes. Instead, miR319 overexpression increased the sensitivity of branching to nitrogen limitation and reduced nitrate uptake, thereby increasing the expression of strigolactone synthesis genes. We further show that carbon starvation reduced the transcription levels of miR319-targeted TCPs, independently of miR319 accumulation, and that TCP3 may connect carbon availability to sugar signalling via HEXOKINASE1. Together, our results identify the miR319-targeted TCP module as a positive regulator of shoot branching that links plant architecture to carbon and nitrogen availability.

Plant roots exhibit remarkable developmental plasticity, resulting in the adaptation of growth direction and architecture upon environmental changes. Previously, we demonstrated that inorganic phosphate (Pi) triggers Arabidopsis roots to skew to the left when grown on tilted agar plates. This so-called 'phosphate-dependent skewing' (PDS) is caused by a right-handed (clockwise, CW) circumnutation of the root tip, which is driven by a left-handed (counterclockwise, CCW) cell file rotation (CFR) of epidermal cells in the root elongation zone, and involves the cortical microtubule cytoskeleton (Sheng et al., 2024). In the present study, we demonstrate that NaCl triggers a skewing response in the opposite direction and that all other helical movements are also reversed. Thus, 'Salt-Induced Rightward Skewing' (SIRS) is accompanied by a right-handed (CW) epidermal CFR, a left-handed (CCW) circumnutation of the root tip, and hence, a left-handed (CCW) helical root growth. Comparing different Na+- and Cl- salts revealed that SIRS is predominantly caused by cations, and can be induced by K+ and osmotic stress as well, although Na+ is most efficient. To get further insight into the mechanism underlying this response, we tested candidate genes from an earlier GWAS on root responses to salt stress (Deolu-Ajayi et al., 2019) for their potential involvement. This identified GLT1 and DOB1 as being involved in the root skewing response to Pi and NaCl, respectively. Our findings reveal that Pi and salinity elicit opposing effects on root circumnutation, and hence root skewing and growth direction. Understanding the molecular machinery driving this helical behaviour may help explain adaptive mechanisms, including changes in the spatial architecture of roots, and may facilitate the optimization of crop yield under abiotic stress conditions through breeding or crop management strategies. Our results also shed new light on halotropism, which is typically measured as a change in root growth direction to the right, which in the present study has been identified to represent SIRS.

Barley yellow dwarf virus (BYDV), transmitted by the bird cherry-oat aphid (Rhopalosiphum padi L.), is among the most damaging viral diseases of barley, but the mechanisms underlying resistance to both the virus and its vector remain poorly understood. Here, we investigated resistance associated with the Hordeum bulbosum-derived Ryd4 introgression in the barley hybrid SY Kestrel by integrating behavioural, electrophysiological, physiological and multi-omics analyses with functional validation of defence metabolites. SY Kestrel exhibited constitutive volatile-mediated antixenosis together with strong post-settlement antibiosis characterised by impaired phloem feeding, reduced aphid fitness and suppression of BYDV gene expression 10 days after transmission. Integrated transcriptomic, metabolomic and small RNA analyses revealed coordinated immune activation, chloroplast remodelling and defence metabolism associated with the resistance introgression. Candidate immune regulators were identified both within the refined Ryd4 interval and the surrounding introgressed region. Maintenance of photosystem II function was accompanied by reprogramming of -linolenic acid-derived oxylipin metabolism, while phenylpropanoid and branched-chain amino acid/lysine pathways generated metabolites that directly reduced aphid survival. We demonstrate that the Ryd4 introgression coordinates constitutive vector deterrence with host defence reprogramming to restrict aphid colonisation and suppress BYDV establishment. These results provide a mechanistic framework for improving durable resistance to aphid-transmitted viruses in cereals.

Reproductive stage drought disrupts flag leaf metabolism in rice (Oryza sativa), limiting photoassimilate translocation to developing grains and reducing grain yield (GY). How natural variation in this response relates to GY remains poorly understood. This study combines untargeted metabolomics of flag leaves from 271 indica rice accessions grown under well-watered (WW) and reproductive-stage water-limited (WL) field conditions with genome-wide association studies of 89 annotated polar metabolites. A total of 180 metabolite quantitative trait loci (mQTLs) were identified: 93 detected only under WL, 68 only under WW, and 19 under both conditions, indicating a predominant stress-dependent genetic control; mapping of GY itself detected only four marginal QTLs, none overlapping the mQTLs. Four high-density regions (HDRs) of mQTLs were identified: HDR1-1, detected only under WW conditions and associated mainly with raffinose family oligosaccharides; HDR1-2, HDR4, and HDR11, detected only under WL conditions and associated mainly with tricarboxylic acid cycle intermediates and amino acids. After correcting for genetic relatedness, accessions carrying the favourable haplotype at both HDR1-2 and HDR4 yielded 21.5% more under WL conditions than accessions carrying the unfavourable haplotype at both loci and lost 11.4 percentage points less GY to stress. Accessions carrying the favourable haplotype at only one locus showed a comparable reduction in yield loss. Haplotype-guided variant detection against the 3,000 Rice Genomes Project panel identified major-impact variants in candidate genes, including a polyphenol oxidase at HDR1-2 and tandem cytochrome P450s at HDR4. These hubs are promising, metabolically defined targets for breeding drought-resilient rice.

Water scarcity and increasingly irregular rainfall threaten avocado production in Mediterranean regions, yet the long term physiological responses of mature trees to sustained deficit irrigation remain poorly understood. We conducted a two-year field study integrating continuous monitoring of the soil plant atmosphere continuum, drone-based multispectral imaging, canopy structural analysis, and fruit phenotyping in a mature avocado orchard subjected to three irrigation regimes. The two study years differed markedly in rainfall, providing a unique opportunity to evaluate how environmental conditions modulate tree responses to water limitation. Trees under severe deficit irrigation showed depletion of water in deeper soil layers and a flattened physiological profile, with near-zero diel variation in leaf thickness and trunk water potential, indicating minimal transpiration and decoupling of tree water status from environmental demand. Drone telemetry via NDVI detected stress during fruit growth and maturation, but not during flowering or the new summer leaf flush, revealing greater drought sensitivity at later maturation stages. Although canopy area did not differ among irrigation treatments, canopy surface roughness increased significantly under deficit irrigation, thereby identifying a novel structural indicator of drought stress. Despite large physiological differences among treatments, fruit number remained stable, while fruit weight decreased significantly under severe deficit irrigation, particularly in the wetter year, suggesting that annual rainfall modulates the trade-off between fruit retention and fruit growth. This study provides the first continuous, multi-scale characterization of avocado performance under sustained deficit irrigation in Mediterranean conditions. By integrating plant-based sensors, remote sensing, and artificial intelligence, we reveal previously undescribed stress dynamics and identify new indicators for precision irrigation management in fruit crops.

Climate change is degrading arable soils and imposing chronic abiotic stress on plants. As the primary interface with the soil, the root system is especially vulnerable, and plants respond by remodelling their root system architecture (RSA). Most studies have examined single stresses in isolation and so fail to capture the multifactorial environments in which plants actually grow. Rising salinity impairs development by compromising cellular integrity and triggering cytotoxic responses, and it simultaneously restricts uptake of phosphorus, a macronutrient required for nucleic acid and protein synthesis. Combined stresses can amplify these effects, yet how plants adjust RSA to cope with them remains poorly understood. Here we performed a meta-analysis of public transcriptomic datasets for salinity and phosphate deficiency in Arabidopsis thaliana. Integrating these data with protein-protein interaction modelling and DNA-binding (DAP-seq) analyses, we identified two basic leucine zipper transcription factors, ABF2 and bZIP2, as candidate integrators of the combined-stress response. Characterization of abf2, bzip2 and double mutants revealed RSA alterations and allowed us to identify downstream targets of each factor. Our findings offer new insight into root adaptation under combined stress and represent one of the few comprehensive analyses of how multiple abiotic stressors jointly shape root development and plant fitness.

Plants frequently experience recurrent drought events separated by periods of rehydration. Although drought imposes strong constraints on plant physiology, prior exposure may alter subsequent stress responsiveness through memory-based mechanisms. Here, we investigated whether recurrent drought at distinct developmental stages establishes stress memory in sugarcane and whether this response persists across vegetative propagation. Two genotypes contrasting in drought tolerance and productivity (IACCTC07-8008 and IACSP95-5000, respectively) were grown under greenhouse conditions and subjected to three drought cycles imposed either at tillering or maturation stage. Gas exchange, photochemical performance, leaf water status, primary metabolite profile, and growth traits were assessed across cycles, and vegetative propagules were subsequently evaluated under renewed drought. The first drought cycle imposed strong limitations on carbon assimilation and photochemistry in both genotypes and developmental stages. However, subsequent cycles resulted in attenuated reductions in A and g, improved intrinsic water use efficiency, and partial stabilization of PSII performance, indicating a modified stress-response trajectory. Young plants displayed earlier improvements (from the second cycle), whereas in mature plants this shift was evident mainly during the third cycle. Recurrent drought promoted sustained reorganization of amino acid, carbohydrate, organic acid and polyol metabolism alongside increased root biomass and higher relative water content during later cycles. Importantly, propagules derived from drought-conditioned plants exhibited faster recovery of photosynthetic performance and reduced cumulative physiological impairment under renewed drought, despite showing similar stress sensitivity at maximum water deficit. This persistence of enhanced recovery capacity across vegetative propagation indicates that drought-induced memory was maintained beyond the initially stressed plants. Together, our findings demonstrate that recurrent drought establishes a metabolically imprinted state in clonal sugarcane, integrating physiological adjustment, metabolic reprogramming, and whole-plant acclimation. These results highlight the potential of stress memory as a mechanism supporting resilience in perennial crops exposed to increasingly recurrent drought events.

Plastidial phosphorylase (Pho1) regulates starch metabolism and also modulates photosystem I (PSI) activity. In rice, Pho1 contains an 80 amino acid intrinsically disordered region (IDR), L80, that acts as a negative regulator. While total removal of the IDR boosts seedling growth, flowering time, overall biomass, and grain yield and alters PSI redox properties, the precise underlying regulatory basis remains unclear. To pinpoint IDR regulatory elements, four Pho1 partial-IDR deletion variants ({delta}N, {delta}C, {delta}M, and {delta}N{delta}C) were evaluated. Lines carrying {delta}M and {delta}C exhibited enhanced starch metabolism, yielding larger, heavier grains, and flowered 5 to10 days earlier than wild type. Both d{delta}M and {delta}C share an acidic motif, (E/V)SEEV, identifying it as a primary negative regulator of starch synthesis and floral timing. By contrast, no partial deletion fully mirrored the PSI redox modifications of Pho1{delta}L80. These results demonstrate that starch biosynthesis and flowering are governed by one or more discrete sequence motifs within the middle and C-terminal regions, whereas PSI modulation likely requires the structural integrity of the intact IDR.

Understanding the genetic architecture of ecophysiological traits related to carbon gain and water loss is crucial to develop cultivars tolerant to abiotic stresses and that maintain productivity in the context of climate change. This can be achieved both through experiments in the greenhouse on potted plants under controlled conditions and in the field. However, the stability of genetic determinism of ecophysiological traits across environmental conditions has rarely been evaluated. We studied a grapevine diversity panel grown both in a greenhouse and in the field, to investigate the impact of growing conditions on leaf ecophysiological traits related to leaf morphology, fluorescence, gas exchange and water use efficiency. The correlation structure between traits was conserved within each environment even though, for most traits, cultivars ranking was not conserved between both environments. However, a set of cultivars, sharing the same functioning pattern in terms of gas exchange and fluorescence in both environments, was identified. Single- and multi-environment Genome-Wide Association Studies (GWAS), based on a dense genotyping matrix, were used to dissect the genetic architecture of leaf traits. The Quantitative Trait Loci (QTLs) identified through single-environment analyses differed substantially from those detected using multi-environment ones. Multi-environment approaches highlighted shared QTLs across environments for gas exchange and fluorescence traits. Candidate genes associated with carbon- and water-related functions were further identified in these genomic regions. Despite the weak correlation between greenhouse and field trait values, combining both environments enabled the identification of robust genetic regions associated with ecophysiological traits of interest.

Photosynthesis is acknowledged as a potential target to increase crop yield. Improved photosynthesis may be achieved by conventional breeding, exploiting the available natural genetic variation for photosynthesis traits. This approach is challenging for crops due to limitations in high-throughput photosynthesis phenotyping, the highly polygenic nature of photosynthesis, and its strongly dynamic response to environmental changes. Recent advancements in phenomics make accurate and detailed photosynthesis phenotyping more feasible, with the model species Arabidopsis thaliana paving the way for applications in crops. In this study, we examined photosynthesis parameters over time in the global Arabidopsis HapMap diversity panel exposed to three conditions: optimal nutrient supply, low phosphorus supply and low nitrogen supply. Combined with two previous studies on photosynthesis in response to low temperature, and to a one-step change in irradiance from low light to high light, five high-quality datasets were systematically analysed using the same approach (with one million-maker set, uni- and multi-variate analyses). Our findings emphasize the genetic complexity of photosynthesis, detecting hundreds of significant quantitative trait loci, only a small number of which are robust, and of which most are condition specific. Robust loci, found in multiple conditions, exemplify those suited for conferring higher all-round photosynthesis, and targets for marker-assisted selection, contributing to environmental resilience, while the multitude of small-effect conditional loci suggest that genomic selection approaches may be more suited to improve crop photosynthesis.

Plant cold acclimation emerges from coordinated adjustments in photosynthesis, primary metabolism, and intracellular carbon allocation. Yet, the regulatory role of subcellular metabolite compartmentation in natural variation of cold acclimation remains insufficiently understood. Here, we investigated four Arabidopsis thaliana accessions grown either individually or in bulk to determine how growth configuration and genotype shape the metabolism of sugars and organic acids during cold exposure. Using non-aqueous fractionation, we quantified plastidial, cytosolic, and vacuolar sugar pools alongside whole-cell carbohydrates, organic acids, enzyme activities, photosynthetic parameters, and stress markers. A neural-network classifier revealed that subcellular sugar distribution together with sugar amounts and organic acids provided the strongest discriminatory power among accessions, surpassing photosynthetic traits and enzyme activities. Our findings demonstrate that natural variation in cold acclimation is strongly determined by genotype-specific subcellular metabolite architectures, and that the cultivation strategy modulates these intracellular signatures. We conclude that subcellular compartmentation of metabolites represents a cellular control layer for natural variation of cold acclimation and resilience in Arabidopsis thaliana.

Photorespiration significantly influences terrestrial carbon fluxes, yet empirical measurements of its variability across tree species and temperature conditions remain limited, constraining predictions of vegetation and climate models. We quantified apparent photorespiratory CO2 loss (Lapp) and its temperature response for seven temperate broadleaf tree species in northern Europe, using in situ O2-shift measurements in Uppsala, Sweden during peak summer. Apparent loss was derived as the difference between net CO2 assimilation under ambient (Anet) and O2-free conditions at three leaf temperatures (25, 30, and 35 {degrees}C), spanning typical and heat-wave scenarios. Apparent photorespiratory CO2 loss showed pronounced interspecific variation and increased with temperature, while net photosynthesis remained relatively stable. The ratio of apparent loss to net photosynthesis ({phi} = Lapp/Anet) rose sharply with temperature, reaching species-mean values up to 0.94 at 35 {degrees}C, indicating that photorespiration can represent nearly the entirety of net carbon gain under heat stress even when leaves remain net CO2 sinks. Suppression of photorespiration under N2 and associated changes in leaf temperature systematically reallocated photosynthetic electron transport: the fraction of ambient electron transport rate (ETR) allocated to net CO2 assimilation declined with temperature, whereas the complementary fraction allocated to apparent photorespiratory loss and other O2-dependent sinks increased, with ETR-based apparent loss and its proportional expression rising steeply across the 25-35 {degrees}C range. Together, these in situ flux and partitioning measurements reveal high variability and strong temperature sensitivity in apparent photorespiration among temperate trees. Compared to crop-based parameterisations, the {phi} values we report for temperate trees are substantially higher and more temperature-dependent, providing species-specific constraints that can improve Farquhar-von Caemmerer-Berry-type vegetation model representations of photorespiration in forest ecosystems.

Peptide hormone signaling coordinates plant growth and osmotic stress responses, yet how the transition between these responses is regulated remains poorly understood. Here, we investigated the function of the rice PLANT PEPTIDES CONTAINING SULFATED TYROSINE 8 (OsPSY8) peptide in osmotic stress responses. OsPSY8 was predominantly expressed in root tissues under non-stress conditions, with preferential expression in lateral roots where it promoted root growth. Osmotic stress rapidly reduced OsPSY8 expression in roots through the OsWRKY24 transcription factor. Loss-of-function ospsy8 mutants exhibited enhanced osmotic stress tolerance, whereas OsPSY8 overexpression increased osmotic stress susceptibility. Transcriptomic analyses revealed that disruption of OsPSY8 activated stress-responsive pathways, including those associated with lignin biosynthesis, compatible solute production, cell wall remodeling, and reactive oxygen species (ROS) scavenging, and was accompanied by increased lignin accumulation in roots. In contrast, overexpression of OsPSY8 resulted in maintenance of growth-associated transcriptional programs while suppressing stress-responsive pathways under osmotic stress. Together, these findings identify OsPSY8 as an important regulator of the transition from growth to stress adaptation in rice and suggest that stress-induced repression of PSY signaling is required to disengage growth programs and activate adaptive responses during osmotic stress. Significance StatementCrop survival during drought depends on the ability to transition from growth to stress adaptation. Plant peptide hormones have emerged as important regulators of this critical transition, highlighting the importance of investigating their roles and potential for improving crop resilience. We show that a rice peptide hormone regulates this transition. Under non-stress conditions, this peptide hormone, predominantly expressed in rice roots, promotes root growth while suppressing stress responses. During osmotic stress, expression of the peptide hormone decreases, resulting in activation of stress-responsive pathways, such as lignin biosynthesis and reactive oxygen species scavenging. These findings demonstrate that a peptide hormone coordinates the balance between growth and stress adaptation in rice, with broader implications for understanding and improving crop resilience.

Rising atmospheric CO2 concentrations consistently reduce mineral concentrations in C crops, yet the mechanisms driving this decline - dilution, reduced transpiration-driven mass flow, and altered root nutrient acquisition capacity - have rarely been tested simultaneously under field conditions. Here, we grew two soybean (Glycine max Merr.) varieties with contrasting yield responses to elevated [CO2] (Loda and HS93-4118) at the Soybean Free Air CO2 Enrichment (SoyFACE) facility and quantified the independent contributions of dilution, transpiration, and root uptake to observed changes in tissue mineral concentration and nutrient yield. Elevated [CO2] increased grain yield by 21% and 6% in Loda and HS, respectively, and reduced transpiration by 13-14% across both varieties. A decomposition analysis revealed that while dilution and reduced transpiration each exerted negative effects on tissue nutrient concentrations, with their combined effect representing a 31-40% potential reduction in whole-plant concentration, active root uptake responses were positive for nearly all nutrients, largely offsetting these losses and resulting in observed concentration declines substantially smaller than either mechanism alone would predict. Consequently, whole-plant nutrient yield increased under elevated CO2 for all elements measured, and grain nutrient yield increased for most. The relationship between seasonal transpiration and nutrient yield was steeper under elevated CO2 for most macronutrients, indicating that plants acquired more nutrients per unit water transpired, not less, under elevated CO2. These results demonstrate that root uptake is the dominant compensatory response to elevated [CO2] driven dilution and reduced mass flow in soybean, that nutrient yield is maintained or increased for most elements under elevated [CO2], and that Fe represents a physiologically and nutritionally significant vulnerability in future CO2 environments.

Plants acclimate to low temperatures by remodeling carbohydrate metabolism. Permanent cold at 4/5{whitebullet} C induces well-characterized cold acclimation in plants, including accumulation of starch and soluble sugars. In natural environments, however, annual plants in their vegetative phase more frequently experience chilling nights (0-6{whitebullet} C nights followed by days at least 12{whitebullet} C warmer), whose metabolic consequences remain poorly understood. We investigated Col-0 Arabidopsis thaliana exposed to one or seven chilling nights and quantified central carbohydrate metabolites, starch, photosynthetic parameters, and maximal activities of enzymes linking sucrose synthesis and cleavage. We integrated these time-series data into a biologically constrained augmented neural ordinary differential equation (ANODE) model to infer diurnal reaction-rate dynamics. Chilling nights induced strong accumulation of sucrose, glucose, and fructose, particularly after seven nights. Both measured sucrose phosphate synthase (SPS) capacity and ANODE-predicted SPS rates increased. In contrast to permanent cold acclimation, daytime starch over-accumulation was absent. Thus, lacking starch over-accumulation together with increased SPS rates, chilling nights invoke distinct carbohydrate-partitioning patterns towards sucrose, indicating a fundamentally different acclimation strategy compared to well described permanent cold.