Drought stress severely limits crop productivity, with transcription factors (TFs) playing pivotal roles in plant adaptation. Here, we identify the maize TF ZmWRKY38 as a positive regulator of drought tolerance. CRISPR/Cas9-mediated knockout of ZmWRKY38 increased plant sensitivity to drought compared with the wild type. We demonstrate that ZmWRKY38 binds to the promoter of the sucrose synthase gene ZmSUS2 and represses its transcription. Conversely, ZmSUS2 functions as a negative regulator of drought tolerance, as zmsus2 mutants displayed enhanced drought resistance. Moreover, we identified ZmRIPK2 (RPM1-induced protein kinase 2), a plasma membrane-localized receptor-like cytoplasmic kinase that also negatively regulates drought responses. Under abscisic acid (ABA) or drought stress, ZmSnRK2.10 phosphorylates and activates ZmRIPK2, triggering its partial translocation into the nucleus. Within the nucleus, ZmRIPK2 interacts with and phosphorylates ZmWRKY38, impairing its DNA-binding capacity and thereby alleviating transcriptional repression of ZmSUS2. Together, our results reveal a negative feedback loop in which ZmRIPK2-mediated phosphorylation of ZmWRKY38 fine-tunes the drought stress response through modulation of ZmSUS2 expression. This mechanism illustrates how ABA signaling attenuates drought responses to balance stress adaptation with normal growth.

Higher organisms spread external stimuli from the perceptive tissues to the whole body to achieve systemic responses. In plants, guard cells sense pathogens and close stomata to prevent their entry. We observed that pathogen-infected local leaves transmit the danger status to uninfected distal systemic leaves and trigger their stomatal closure as a global defense termed systemic stomatal immunity (SSIM). The underlying mobile signals remain unknown. Here, we report that an upstream open reading frame (uORF)-encoded systemic stomatal immune conductor (USIC) acts as a long-distance mobile peptide inducing SSIM. In local leaves, USIC increases upon pathogen/pattern signals and is secreted into the apoplast for long-distance transport. In systemic leaves, USIC is perceived by the cell surface SUCROSE-INDUCED RECEPTOR KINASE 1 (SIRK1)-KINASE 7 (KIN7) receptor complex and induces METACASPASE 4 (MC4)-mediated KIN7 cleavage. KIN7 associates with proton pumps/aquaporins to regulate stomatal closure. This study reveals a systemic signaling mechanism whereby an uORF-encoded mobile signal and its receptor pathway activate SSIM.

Drought threatens global crop yields, and common oat, a vital nutritional source for food and feed, is particularly constrained in the semi‑arid regions where it is widely cultivated. Here, we report two high-quality genome assemblies for drought-resilient (Borris37) and drought-sensitive (XymC06) oat accessions with distinct seedling survival rates and genome sizes of 10.92 Gb and 10.96 Gb, and construct comprehensive landscapes of insertion‑deletions (InDels) and structural variants (SVs). Integrating population-level genomic, transcriptomic and phenotypic (seedling survival rate), we demonstrate that InDels and SVs underpin divergent drought resilience and identify 52 candidate genes associated with drought resistance whose expression is significantly modulated by these variants. Borris37 accumulates 36 favorable alleles of these genes. An InDel in the AsNF-YB3 promoter enhances binding to AsARF1, upregulating AsNF‑YB3 under drought, and overexpression of AsNF‑YB3 reduces ROS accumulation. Our findings provide resources and targets for drought‑resistance breeding in oat, thereby supporting global food security. Drought severely constrains common oat production. By generating genome assemblies for oat accessions with contrasting drought tolerance, the authors identify genetic variants and candidate genes underlying drought resistance, including an NF-Y transcription factor and its putative upstream regulator.

Salt stress is a major abiotic constraint limiting global crop production. Oat (Avena sativa L.), an allohexaploid cereal renowned for robust stress tolerance, remains poorly understood in terms of the molecular mechanisms underlying its response to salt stress. Here, we perform transcriptome profiling across multiple developmental stages and tissues of oat under salt stress, and construct the co-expression regulatory network to identify salt tolerance-associated gene modules. Notably, 10 salt-responsive transcription factor (SRTF) families with dynamic expression patterns are identified as core regulators, showing extensive subgenomic functional divergence, characterized by subgenome-dominant expression, as well as subgenome-specific duplication or loss events. Further integration with a genome-wide association study (GWAS) of the germination rate under salt stress in 225 oat accessions identified a 3-bp InDel variation within the duplicated gene AsWRKY49-D2, which specifically modulates its expression by facilitating binding of the TF AsZAT18, with AsWRKY49-D2 further mediating oat salt tolerance through targeted regulation of AsSOS2 and AsSOS3. Intriguingly, the salt-tolerant allele of AsWRKY49 is scarcely distributed in Chinese oat accessions, highlighting its considerable potential for breeding application. These results shed light on the regulatory mechanisms underlying oat salt tolerance, providing valuable information for exploring salt tolerance genes and breeding new salt-tolerant oat varieties.

Guard cell movement is orchestrated by complex internal and environmental signals, with ZmGCT1 and ZmGCT2 playing critical roles in maintaining guard cell turgor in maize. Here, we demonstrate that ZmGCT1 interacts with and inhibits ZmSK4, a GSK3-like kinase. Under drought stress, ABA-activated ZmSnRK2s phosphorylate ZmGCT1, relieving its partial inhibition of ZmSK4, which, together with the relief of ZmPP2Cs-mediated inhibition, leads to ZmSK4 activation. ZmSK4 directly phosphorylates ZmSLAC1 and activates its anion currents in Xenopus oocytes, which ultimately promotes stomatal closure under drought stress. Consistent with this mechanism, mutations in ZmSK4 and its homolog ZmSK3 not only confer drought sensitivity but also suppress the constitutively closed stomata phenotype of the Zmgct1 mutant. Notably, in contrast to its BIN2 homologs, which do not regulate stomatal movement in Arabidopsis but stomatal development, ZmSK4 and ZmSK3 do not influence stomatal development in maize. Our findings thus delineate a complete phosphorylation relay within the ABA signaling pathway that dynamically regulates stomatal movement under drought stress in maize.

Climate warming poses increasing thermal challenges to plants, yet how plasma membrane biophysics contributes to heat adaptation remains poorly understood. In this work, we showed that the malectin-like receptor kinase FERONIA (FER) acts as a membrane-anchored thermal switch in Arabidopsis . FER organizes sterol-dependent nanoclusters that control heat acclimation. Moderate heat activated FER through the RAPID ALKALINIZATION FACTOR 34 (RALF34) peptide and promoted its recruitment to sterol-rich nanodomains. There, FER nucleated dynamic nanoclusters enriched in stress-signaling components. These nanoclusters stabilized liquid-ordered membrane phases and activated heat shock transcription factor–heat shock protein signaling, enhancing thermotolerance. However, under extreme heat the nanoclusters rapidly disassembled, preventing maladaptive responses. Our findings thus establish nanoscale membrane compartmentalization as a key mechanism linking lipid dynamics to plant thermal resilience.

Cold stress restricts plant growth and inorganic phosphate (Pi) uptake, reducing yield and increasing fertilizer demand1-3. Enhancing both cold tolerance and phosphorus use efficiency (PUE) is crucial for sustainable crop productivity. Here we identify the SPX-domain-containing E3 ubiquitin ligase NITROGEN LIMITATION ADAPTATION (NLA) as a central regulator that links cold signalling to Pi homeostasis in maize (Zea mays L.). Under cold conditions, NLA promotes the degradation of the transcriptional repressor JAZ11, activating jasmonate signalling to enhance cold tolerance; however, NLA also simultaneously represses Pi uptake, through inositol polyphosphate (InsP)-dependent ubiquitination of the Pi transporter PT4. A ubiquitinome-informed genome-wide association study identified a natural PT4(K267A) (lysine-to-alanine substitution) variant that attenuates NLA-mediated degradation and increases Pi uptake in cold conditions. To overcome this nutrient-stress trade-off, we combined artificial-intelligence-guided structural modelling and ligand docking with genome editing to generate the nlaΔ12 allele, which encodes an NLA variant in which binding to InsP is impaired but JAZ11 targeting is retained. The Δ12 modification selectively redirects the activity of NLA towards jasmonate signalling, resulting in improved cold resilience, higher PUE and increased yield in multi-site field trials. These findings reveal a tunable SPX regulatory module that integrates environmental and nutrient signals, and provide a molecular framework for engineering climate-resilient, nutrient-efficient crops.

Transcription factors (TFs) play a critical role in regulating the expression of drought-responsive genes. Elucidating how TFs are modulated by stress signals will contribute to deciphering the impacts of drought on transcriptional regulation. We discovered that the mutation of an HD-Zip IV TF ZmOCL1 (OUTER CELL LAYER1) enhances susceptibility to water deficit. Transcriptome analysis and biochemical evidence demonstrated that a dehydrin gene ZmDHN2 is one of the direct target genes of ZmOCL1. Overexpression of ZmDHN2 in maize confers drought resistance by regulating stomatal closure, elevating peroxidase activity, and reducing hydrogen peroxide accumulation. Screening for an upstream kinase of ZmOCL1 identified a mitogen-activated protein kinase (MAPK) ZmMPK5, which is activated by dehydration. ZmMPK5 phosphorylates ZmOCL1 at the Ser283 residue and increases its binding affinity to the ZmDHN2 promoter, leading to full induction of ZmDHN2. Overexpression of ZmMPK5 improves drought tolerance and raises the transcription of ZmDHN2 compared to wild-type maize, while knockout of ZmMPK5 results in sensitivity to drought and a decrease in ZmDHN2 transcription. Our work reveals a transcriptional regulatory module in which ZmOCL1 promotes the expression of ZmDHN2 after being phosphorylated by ZmMPK5 in response to drought stress, finally resulting in better adaptation to water scarcity.

Mini-Chromosome Maintenance 10 (MCM10) is essential for maintaining genome stability by facilitating DNA replication and repair across various organisms. While the role of MCM10 in DNA replication is well-established, its mechanism in DNA repair remains less understood. In this study, we demonstrate that loss of AtMCM10 function leads to increased DNA damage under genotoxic or salinity stress in Arabidopsis thaliana. Detailed analysis reveals that AtMCM10 works primarily downstream of ATM and is crucial for intermolecular homologous recombination (HR) mediated by synthesis-dependent strand annealing (SDSA) in response to DNA damage. Further cytological and biochemical analyses reveal that AtMCM10 possesses DNA annealing activity, colocalizes with the double-strand break (DSB) sites, and undergoes liquid-liquid phase separation (LLPS) upon DNA damage, facilitated by single strand DNA (ssDNA) in vitro. Altogether, our findings indicate that AtMCM10 acts as a single-strand DNA (ssDNA) annealing protein to promote SDSA-mediated intermolecular HR repair via LLPS in somatic cells upon DNA damage, providing new insights into the HR repair mechanisms.

Drought stress represents a critical challenge to global agriculture, severely compromising plant growth and crop productivity through its disruption of intracellular signaling networks, with particular emphasis on protein kinase-mediated pathways and transcriptional regulation. In this study, we identified and characterized ZmDNL1 as a novel transcriptional regulator that serves as a negative modulator of drought tolerance in maize. Through comprehensive biochemical analyses, we demonstrated that ZmDNL1 physically interacts with ZmYAB15, a known negative regulator of drought tolerance, and potentiates its transcriptional regulatory activity. Most significantly, our investigation revealed that ZmSnRK2.10-mediated phosphorylation of three specific N-terminal residues in ZmDNL1 effectively attenuates ZmYAB15's transcriptional activity while maintaining the structural integrity of the ZmDNL1-ZmYAB15 protein complex, ultimately enhancing drought tolerance. These findings elucidate a previously unrecognized regulatory mechanism in which ZmSnRK2.10 orchestrates drought tolerance through phosphorylation-dependent fine tuning of the ZmDNL1-ZmYAB15 transcriptional regulatory module. Beyond advancing our fundamental understanding of drought response mechanisms in maize, this study provides valuable molecular targets for precision breeding strategies aimed at developing drought-resilient crop varieties.

In recent years, global climate change has intensified the effects of critical environmental stressors, such as drought, flooding, and extreme temperatures, on plant growth and crop yield. Drought stands out as a major meteorological hazard due to its high frequency, prolonged duration, and widespread impact. Drought is not only prevalent in arid and semi-arid regions, but may also trigger stress in areas with higher annual precipitation where uneven distribution occurs during the growing season. As a significant abiotic stress, drought constrains plant growth and diminishes crop yields. A deeper understanding of drought's effects on plant growth and development, the molecular regulatory networks underlying plant responses to drought stress, and the exploration of drought-resistant gene resources will advance the establishment and expansion of the theoretical framework in plant stress biology. These efforts will further provide theoretical foundations and genetic resources for molecular design breeding of drought-resistant crops. This review summarizes major advances in drought resistance research in Arabidopsis thaliana and major crops. The first section elucidates the signal transduction pathway of abscisic acid (ABA) and the molecular mechanisms of transcriptional regulation in response to drought stress. Under drought conditions, formation of the ABA complex (PYR/ PYL/RCAR-ABA-PP2C) releases SnRK2 protein kinases, which subsequently phosphorylate and activate downstream transcription factors (ABI5 and AREBs). These transcription factors bind to ABA-responsive elements (ABREs) in the promoters of ABA-dependent genes. Meanwhile, DREB transcription factor, also known as CBFs, regulates the stress-inducible expression of genes via ABA-independent pathways. The promoters of these drought-responsive genes frequently harbor the dehydration-responsive cis-element (DRE). Drought detrimentally affects plants by reducing germination, suppressing leaf expansion and tillering, diminishing dry matter accumulation, and decreasing grain yield. Plants have evolved physiological and molecular mechanisms to mitigate these damaging effects. The second section details the molecular mechanisms of drought stress signal perception and transduction, as well as the impact of drought on plant growth and development. Specific aspects include leaf epicuticular wax deposition, stomatal development and movement, root growth, and reproductive development. Here, we summarize recent progress in cloning and functionally characterizing drought resistance genes, alongside technological advances developed to alleviate drought's threat to crop production. Our results further suggest that the integration of multi-omics data, more reference genome information, and robust statistical analyses is likely to facilitate the identification of other causal genes associated with drought resistance. Elucidating how plants perceive and respond to drought stress at the molecular level is fundamental to developing molecular approaches for enhancing crop tolerance. Molecular breeding approaches, such as marker-assisted selection, gene pyramiding, and genome editing, can fully utilize the growing repository of favorable alleles to precisely improve drought-resistant traits. Finally, this article summarizes representative achievements in drought resistance research over the past four decades (1984-2024) from the College of Biological Sciences at China Agricultural University. These findings provide both theoretical foundations and genetic resources for molecular design breeding of drought-tolerant and water-saving crop varieties.

Avena fatua (weedy oat) is a globally pervasive weed, notorious for its adaptability to extreme environments and herbicide tolerance. Here, we present the 10.98-Gb hexaploid genome of A. fatua and a variation map from 768 wild and cultivated oats (A. fatua, A. sterilis and A. sativa), elucidating their genetic relationship and evolutionary history. Population genomic analyses reveal genetic connections between A. fatua and cultivated naked oats, and identify divergent regions between A. fatua and A. sativa enriched in genes associated with biotic and abiotic stresses. Among them, a herbicide-resistance locus is identified on chromosome 4D, with A. fatua accessions carrying a highly differentiated haplotype from cultivated oats. Multi-omics profiling and functional validation demonstrate that one expanded GST gene in this locus contributes significantly to oat herbicide resistance. Our study provides genomic resources for understanding A. fatua's broad adaptability to diverse environmental conditions, facilitating the development of climate-resilient oat varieties.

Epigenetic mechanisms are integral to plant growth, development, and adaptation to environmental stimuli. Over the past two decades, our comprehension of these complex regulatory processes has expanded remarkably, producing a substantial body of knowledge on both locus-specific mechanisms and genome-wide regulatory patterns. Studies initially grounded in the model plant Arabidopsis have been broadened to encompass a diverse array of crop species, revealing the multifaceted roles of epigenetics in physiological and agronomic traits. With recent technological advancements, epigenetic regulations at the single-cell level and at the large-scale population level are emerging as new focuses. This review offers an in-depth synthesis of the diverse epigenetic regulations, detailing the catalytic machinery and regulatory functions. It delves into the intricate interplay among various epigenetic elements and their collective influence on the modulation of crop traits. Furthermore, it examines recent breakthroughs in technologies for epigenetic modifications and their integration into strategies for crop improvement. The review underscores the transformative potential of epigenetic strategies in bolstering crop performance, advocating for the development of efficient tools to fully exploit the agricultural benefits of epigenetic insights.

The calcineurin B-like protein (CBL)-CBL-interacting protein kinase (CIPK) Ca²⁺ sensors play crucial roles in the plant's response to drought stress. However, there have been few reports on the synergistic regulation of drought stress by CBL-CIPK and abscisic acid (ABA) core signaling components. In this study, we discovered that ZmCIPK33 positively regulates drought resistance in maize. ZmCIPK33 physically interacts with and is enhanced by phosphorylation from ZmSnRK2.10. Drought stress can activate ZmCIPK33, which is partially dependent on ZmSnRK2.10. ZmCIPK33 in combination with ZmSnRK2.10 can activate the slow anion channel ZmSLAC1 in Xenopus laevis oocytes independently of CBLs, whereas ZmCIPK33 or ZmSnRK2.10 alone is unable to do so. Furthermore, ZmCIPK33 phosphorylates ZmPP2C11 at Ser60, which leads to a reduction in the interaction between ZmPP2C11 and ZmEAR1 (the ortholog of Arabidopsis Enhancer of ABA co-Receptor 1) and weakens the phosphatase activity of ZmPP2C11, consequently, enhancing the activity of ZmSnRK2.10 in an in vitro assay and in the in-gel assay of the zmcipk33 mutant. Our findings provide novel insights into the molecular mechanisms underlying the reciprocal enhancement of Ca²⁺ and ABA signaling under drought stress in maize.

Dear Editor, Common oat(Avena sativa,2n=6×=42,AACCDD),with global production ranking seventh among cereals(),is an economically important worldwide food and livestock feed with strong adaptability to various harsh marginal environments(Rasane et al.,2015).Genomic studies and molecular breeding of oat lag far behind those of other agriculturally important crops due to its considerable genome size(～11 G),highly repetitive sequences(86.95％)(Peng et al.,2022),and high ploidy.Although three hexaploid oat genomes-OT3098(),Sang(Kamal et al.,2022),and Sanfensan(Peng et al.,2022)-have been released,they are insufficient to capture the full genetic diversity of cultivated oats.

Persistent activation of drought tolerance is detrimental to plant growth and development. However, the mechanism that balances plant drought tolerance and growth remains largely undetermined. Here, we constructed a comprehensive co-expression network comprising 84 transcriptome datasets associated with growth and drought tolerance in oats. Moreover, 84 functional modules and many candidate genes related to drought tolerance and growth were identified. A key candidate gene, AsHSFA2c was involved in fine-tuning the balance between drought tolerance and growth by inhibiting plant growth and positively regulating drought tolerance. Then, we determined AsDOF25 as an upstream positive regulator and AsAGO1 as the downstream target gene of AsHSFA2c. These results imply that the AsDOF25-AsHSFA2c-AsAGO1 module contributes to the balance between drought tolerance and growth in oats. Our findings and resources will facilitate the identification of key genes related to drought tolerance and further studies of the genetic basis underlying strong drought tolerance in oats.

In higher plants, stomatal movements represent a critical physiological process that matains cellular water homestasis while enabling photosynthetic gas exchange. Open stomata 1 (OST1), a key protein kinase in the abscisic acid (ABA) signaling cascade, has been established as a central regulator of stomatal dynamics. This study reveals that two highly conserved mitogen-activated protein kinase 1 (MAP4K1) and MAP4K2 are positive regulators in ABA promoted stomatal closure, and ABA-activated OST1 potentiates MAP4K1/2 through phosphorylation at conserved serine and threonine residues (S166, T170, and S479/S488). The activated MAP4K1, in turn, phosphorylates two critical downstream targets: plasma membrane H+-ATPase 2 (AHA2) at residues T858, T881, and Y946, and slow anion channel-associated 1 (SLAC1) at T114 and S116. Functional analysis demonstrates that the phosphomimetic (3D: S166D/T170D/S479D) MAP4K1, but not non-phosphorylatable (3A: S166A/T170A/S479A) MAP4K1, could fully restore drought tolerance and reduced water loss in detached leaves of map4k1map4k2 double mutant. Our findings delineate a previously unrecognized signaling module comprising OST1-MAP4K1/2-AHA2/SLAC1, which crucially modulates ABA-mediated stomatal regulation. This work advances our mechanistic understanding of phosphorylation cascades governing plant water relations and stress responses.