Stomata are pivotal for gas exchange during photosynthesis and transpiration and are therefore critical in plant growth and global water cycles. However, the mechanistic role of cell wall architecture in grass stomatal function remains elusive. Here immunolabelling and mechanical mapping revealed local distribution of methylesterified pectin at the stiffer polar ends of maize stomata. Expression-knockdown maize with reduced pectin labelling showed decreased polar stiffness and increased stomatal aperture. Finite element modelling corroborated these findings, suggesting that in contrast to non-grass stomata, the size and modulus of the polar materials limit maize stomatal opening. Surveys from various plant species suggest that polar-enriched methylesterified pectin is a unique feature of grass stomata. Xylanase pretreatment diminished pectin labelling at the polar ends, implying associations between pectin and xylan. Our multi-scale research uncovers a pectin-xylan-cellulose composite mediating polar fixation during maize stomatal movement, unveiling new targets for stomata engineering and crop breeding.

Laticifers are specialized secretory cells that synthesize and store latex and provide a model for studying cellular specialization in plant metabolism. Euphorbia lathyris L. possesses non-articulated laticifers that produce triterpenoid-rich latex, but the mechanistic basis of laticifer specialization and latex metabolism remains unclear. Here, we generate the single-nucleus transcriptomic landscape of E. lathyris leaves and resolve a continuous laticifer trajectory with progressive activation of the mevalonate-derived triterpenoid pathway. Genes encoding the rubber biosynthetic complex, including cis-prenyltransferase (CPT), CPT-binding protein (CBP), and small rubber particle protein (SRPP), were specifically expressed in laticifers, indicating potential rubber formation. Ultrastructural and chemical analyses detect small rubber particles (similar to 150 nm) and a low-abundance cis-1,4-polyisoprene fraction in latex (0.30-0.47% w/w) with short average chain length (Mw approximate to 150-180 kDa). The streamlined repertoire of rubber biosynthetic pathway genes and the absence of Hevea-like rubber elongation factors (REFs) may be associated with the observed low rubber content and smaller molecular weight in E. lathyris. Network inference and validation identified a laticifer-specific DOF transcription factor, COGWHEEL1 (ElCOG1), that binds the promoters of ElCPT1 and butyrospermol synthase 1 (ElBUT1) and represses their activity, indicating a shared negative transcriptional control point acting on both the rubber-elongation and triterpenoid branches. In summary, this single-nucleus transcriptomic landscape of E. lathyris laticifers clarifies their metabolic specialization and establishes a framework for dissecting the regulatory programs of specialized secretory cells in latex-bearing plants.

Gibberellin (GA) biosynthesis and signaling play important roles in seed setting and grain weight; however, how long-distance GA transport contributes to these traits remains poorly understood. Here, we characterized the Nitrate transporter 1/Peptide transporter Family (NPF) protein OsNPF3.5, which mediates GA allocation in rice (Oryza sativa L. var. Nipponbare). OsNPF3.5 was preferentially expressed in the phloem of the leaf blade at the reproductive stage and was responsive to lower temperatures. Ectopic expression of OsNPF3.5 in Xenopus laevis oocytes showed relatively low uptake activity for GA3,4,7 and abscisic acid (ABA) but a significant efflux activity for GA44 across the plasma membrane. Compared with the wild type, pollen fertility, seed-setting rate, 1,000-grain weight, and grain yield were decreased in osnpf3.5. Moreover, functional disruption of OsNPF3.5 essentially decreased GA44 redistribution from the flag leaf blade and was accompanied by decreased levels of GA3 in anthers and GA1 in caryopses. These results suggest that OsNPF3.5 functions as a GA44 efflux transporter promoting GA44 loading into phloem, thus facilitating GA allocation from flag leaf blade to sink organs including anthers and caryopses, which consequently regulates seed setting, 1,000-grain weight, and grain yield. This represents a mechanism by which long-distance GA precursor transport gets involved in rice seed setting and grain weight formation under variable environmental conditions.

Cross-compartment communication is critical for maintaining cellular homeostasis, which is essential for cell function and survival under stressful conditions. However, the cellular cues that trigger interorganellar communication remain poorly understood. Mitochondrial Ca2+ (mtCa2+) homeostasis is fundamental to mitochondrial function; yet, how mitochondrial Ca2+ (mtCa2+) homeostasis modulates nuclear gene expression to establish and maintain cellular homeostasis remains unclear. Here, we first characterize the critical role of the mitochondrial Ca2+ uniporter (MCU) in control of mtCa2+ uptake and maintaining mtCa2+ homeostasis in planta. Using gain-of-function and sextuple MCU knockdown mutants, we then analyzed the effects of impaired MCU-controlled mtCa2+ homeostasis (iMUCH). We find that iMUCH elicits an interorganellar transcription program that activates multiple compartment-specific unfolded protein responses (UPRs) and genes critical for mitochondrial and cytosolic proteostasis. Additionally, iMUCH induces a post-transcriptional program that selectively represses the synthesis of ribosomes and RNA modification proteins. Furthermore, eukaryotic initiation factor α (eIFα and its phosphorylation likely serve as a protective mechanism under long-term mitochondrial proteotoxic stress induced by iMUCH. Collectively, the data demonstrate that MCU-controlled mtCa2+ homeostasis plays a pivotal role in sustaining mitochondrial and cytosolic proteostasis through an interconnected organelle quality control system, which ultimately determines cell growth and fitness.

Reactive oxygen species (ROS) function as essential signaling molecules regulating diverse processes in plants. However, the mechanisms by which plants accurately perceive and distinguish between physiological and stress-induced ROS signals to coordinate growth and stress responses remain largely unclear. Here, we show that Radical-induced Cell Death1 (RCD1) functions as a redox sensor that undergoes a ROS-triggered phase separation transition. Three cysteine residues within RCD1 regulate the formation of phase-separated condensates, and the transition between condensate and non-condensate states determines the spatiotemporal interactions of RCD1 with the leaf morphogenesis-related transcription factor ASYMMETRIC LEAVES1 (AS1) or the stress-responsive zinc-finger transcription factor ZAT12. Through this mechanism, RCD1 phase separation differentiates growth- and stress-related ROS signals to orchestrate downstream gene regulation. The dynamic formation of transcriptional condensates and ROS-induced phase separation transition allow plants to rapidly distinguish and respond to developmental and environmental cues, potentially representing a conserved mechanism in eukaryotes.

During development, cell fate determination hinges on the dynamic activities of multiple transcription factors (TFs), but how the activities of individual TFs contribute to developmental diversity remains incompletely understood. Here, we report that BZU2/ZmMUTE is responsible for the functional and spatial heterogeneity of the four-celled stomatal complexes in maize (Zea mays), in part through its liquid-liquid phase separation (LLPS) property. Genotypic and single-cell RNA-seq analyses confirmed previous findings that ZmMUTE is associated with lineage-specific gene expression during stomatal development, while providing additional resolution of cell-type-specific transcriptional programs. The intrinsically disordered region 4 (IDR4) promotes the formation of ZmMUTE condensates, which can recruit the ZmMUTE partner ZmSCRM and associate with transcriptionally active sites. These condensates are associated with enhanced DNA binding and target gene activation, potentially influencing the development of guard cells and subsidiary cells. IDR4 is also sufficient for conferring cell-to-cell mobility to AtMUTE, highlighting its conserved role in facilitating intercellular movement. Taken together, the dynamic behavior of ZmMUTE, owing to its condensational properties, appears to orchestrate cell-type-specific regulation, thereby enabling the emergence of the unique four-celled stomatal morphology.

Secondary xylem differentiation determines wood structure and function in perennial plants, yet its regulatory mechanisms remain poorly understood in Hevea brasiliensis. Here, we generated a single-nucleus RNA sequencing (snRNA-seq) atlas from the cambium to mature xylem region in stems, resolving transcriptionally distinct cell populations corresponding to cambium, xylem mother cells, and fibre-vessel cells. Pseudotime analysis reconstructed the developmental trajectories from cambium to late xylem cell states and revealed stage-specific activation of secondary cell wall (SCW) biosynthesis programmes. Gene regulatory network analysis identified HbWRKY12a as a fibre-vessel enriched transcription factor functioning as a key regulator in SCW formation. Molecular assays demonstrated that HbWRKY12a directly binds and activates HbMYB1R1c, which subsequently modulates lignin-associated SCW deposition. Heterologous overexpression of either HbWRKY12a or HbMYB1R1c in Arabidopsis resulted in significant reductions in stem diameter and plant height. Both overexpression lines exhibited markedly decreased SCW thickness in fibre, vessels, and pith cells. These findings reveal a WRKY-MYB cascade that mediates SCW formation in H. brasiliensis, extending the classical NAC-MYB regulatory framework and providing molecular targets for improving xylem properties and stress resilience in tropical perennial crops.

Asymmetric cell division underpins cellular diversity in multicellular plants. These divisions are mechanosensitive, and preprophase band (PPB) formation hinges on cell-wall mechanical properties in plant cells. Yet, the spatial control mechanism governing this process in plants remains elusive. During grass stomatal development, mechanical cues originate from differential growth rates and cell wall modifications at the interface of guard mother cell/subsidiary mother cell (SMC). In this work, we have identified a maize receptor-like protein, KAI1, that functions as a master regulator of subsidiary cell formation within the stomatal complex. KAI1 governs division-plane orientation in SMCs through mechanochemical signaling: It perceives cell wall rigidity via pectin interaction, and subsequently recruits tubulin for PPB positioning, thereby directing division-plane specification. This work uncovers a plant-unique mechanosensitive protein that mediates extracellular matrix cues to cytoskeletal reorganization during asymmetric division for cell diversity. Our findings establish that KAI1 governs a cell wall mechanics-dependent PPB positioning to control the exact division plane alignment of the SMC. This mechanism subsequently mediates the regulation of SMC polarization and subsidiary cell morphogenesis during stomatal development.

This Editorial introduces the Virtual Issue ‘Stomata’ that includes the following papers: Apigo et al . (2026), Bernardo et al . (2026), Brench et al . (2026), Busby et al . (2026), Caine et al . (2019, 2026), Chen et al. (2026), Ding et al . (2026), Drake et al . (2019), Erberich et al . (2026), Fan et al . (2025), Grenzi et al . (2026), Gustavsson et al . (2026), Hõrak (2026), Huang et al . (2026), Kou et al . (2026), Li et al . (2026), Liu et al . (2025), Nguyen et al . (2026), Raven (2002), Roelfsema & Hedrich (2002), Samantara et al. (2025), Sicangco et al . (2026), Silva‐Alvim et al . (2026), Sinha et al . (2022), Song et al . (2014), Sun et al . (2025, 2026), Tan et al . (2026), Wilson et al . (2025), Woning et al . (2026), Yan et al . (2026), Yang et al . (2026), Zavala‐Paez et al . (2026), Zhang et al . (2025). Access the Virtual Issue at www.newphytologist.com/virtualissues .

Plant stomata are microscopic leaf pores that regulate gas exchange but also serve as pathogen entry points and frontline sensors for stresses like drought. This review synthesises current understanding of stomata's dual defensive roles in coordinating responses to pathogen invasion and drought stress, highlighting sophisticated synergistic and antagonistic mechanisms governing stomatal dynamics under combined pressures. Guard cells integrate diverse stress signals through complex, overlapping signalling networks involving mitogen-activated protein kinase cascades, reactive oxygen species bursts, Ca2+ oscillations, and small signalling peptides. Functioning as pivotal nodes in the evolutionary 'arms race' between plants and pathogens, stomata exhibit significant crosstalk between abscisic acid-mediated drought responses and pathogen-associated molecular patterns-triggered immunity. Drought-induced closure can paradoxically create pathogen-favourable microenvironments, while pathogen signals modulate long-term stomatal development. Critical unresolved questions concern defence-growth trade-offs, signalling pathway interference, and tissue-specific functional redundancy. Cutting-edge techniques like single-cell sequencing and synthetic biology are revolutionising understanding and enabling engineering approaches. Recognising stomata as central hubs for hierarchical environmental adaptation is crucial for developing strategies to enhance crop resilience against increasing compound stresses under climate change, particularly through engineering optimised stomatal responses for concurrent drought tolerance and disease resistance.

Wheat is a major staple crop for over one-third of the world's population, crucial for global food security, economic stability and cultural traditions. Recently, single-cell and spatial omics approaches have transformed biological discovery, primarily in medical and animal sciences, and they are now beginning to be applied in plant research. Here we summarize the technical innovations and feasibility of spatial omics applications in wheat research, particularly for understanding developmental and environmental responses, thereby potentially enhancing wheat breeding. We highlight how these tools can reveal spatial and temporal patterns in gene expression, cellular heterogeneity and tissue organization in wheat. Furthermore, we propose developing a spatially resolved single-cell atlas of wheat across its life cycle to facilitate breakthroughs in basic research and potential applications in breeding. To achieve these goals, we advocate for a Wheat Spatial Omics Consortium to foster worldwide collaboration for overcoming barriers and developing sustainable and climate-resilient wheat.

Cotton fiber length is a crucial attribute that significantly affects yarn production and fabric quality, making it a primary focus in cotton breeding efforts. Both current and previous studies have indicated a lack of correlation between fiber length and gene expression dynamics, underscoring the importance of phenotyping fiber elongation. Traditional methods for measuring fiber length, however, tend to be impractical and labor-intensive, particularly for developing fibers that are fragile and prone to twisting. In this study, we present an innovative phenotyping method to measure the elongation of developing cotton fibers. Our key findings reveal a strong linear relationship between the total volume of fiber bundles and fiber length. This relationship allows for the straightforward estimation of the linear correlation coefficient from the final fiber length and the final volume of the fiber bundle within a boll. Upon measuring both the fiber bundle volume and fiber length, we discovered that their growth dynamics were well-represented by a logistic curve. Additionally, the expression dynamics of several newly identified genes demonstrated a significant positive correlation with the rate of fiber elongation. This research marks an important advancement in quantifying gene expression dynamics and fiber elongation. We believe that measuring the elongation of developing fibers will greatly accelerate the development of high-quality cotton varieties and enhance our understanding of plant developmental biology.

Abstract Abscisic acid (ABA) is a central regulator of plant growth and stress responses. However, it also negatively impact germination, growth, and reproductive performance, highlighting the need for mechanisms that fine-tune its signalling. Here, we identify γ-aminobutyric acid (GABA) as an endogenous antagonist of plant ABA receptor. We show that GABA binds the clade A protein phosphatase–ABI1, disrupting its association with the ABA receptor PYL1, blocking ABA binding, thereby attenuating ABA signalling. GABA modulates ABA-control of stomatal aperture and seed germination, demonstrating its broad physiological influence. Notably, GABA accumulation during stress coincides with the subsequent decline in ABA, consistent with a delayed feedback signal of ABA activity. Together, this work identifies GABA as an antagonist of ABA and provides a mechanism balancing plant stress resilience and growth.

Mitogen-activated protein kinase (MAPK) cascades regulate growth, development, stress responses, and immunity in plants by transmitting signals from upstream regulators to downstream components. In this study, we identify a MAPK cascade composed of MAPK kinase kinase 19 (MKKK19), three MAPK kinases (MKK3/MKK5/MKK9), and MAPK 6 (or MPK6) that is involved in Arabidopsis leaf senescence. The kinase oxidative signal-inducible 1 (OXI1) functions upstream of the MKKK19-MKK3/MKK5/MKK9-MPK6 cascade to promote leaf senescence, whereas two of RESPIRATORY BURST OXIDASE HOMOLOGS (RBOHs), RBOHD and RBOHF, act downstream to mediate the accumulation of reactive oxygen species (ROS). Loss-of-function mutation of OXI1, MKKK19, MKK3/MKK5/MKK9, or MPK6 resulted in delayed leaf senescence associated with reduced ROS levels, whereas transgenic lines overexpressing OXI1, MKKK19, MKK3/MKK5/MKK9, or MPK6 displayed the opposite phenotypes. Epistatic analyses supported the involvement of OXI1, MKKK19, MKK3/MKK5/MKK9, MPK6, and RBOHD/RBOHF in the same signaling pathway for leaf senescence. In conclusion, genetic and biochemical analysis of the Arabidopsis MKKK19-MKK3/MKK5/MKK9-MPK6 cascade through OXI1 and RBOHD/RBOHF revealed a vital role for the MAPK cascade and ROS in natural leaf senescence.

Mitochondria support plant growth and adaptation via energy production and signaling pathways. However, how mitochondria control the transition between growth and stress response is largely unknown in plants. Using molecular approaches, we identified the histone H3K4me3 demethylase JMJ15 and the transcription factor CRF6 as targets of SnRK1 in Arabidopsis. By analyzing antimycin A (AA)-triggered mitochondrial stress, we explored how SnRK1, JMJ15, and CRF6 form a regulatory module that gauges mitochondrial status to balance growth and the oxidative stress response. SnRK1a1, a catalytic α-subunit of SnRK1, phosphorylates and destabilizes JMJ15 to inhibit its H3K4me3 demethylase activity. While SnRK1a1 does not phosphorylate CRF6, it promotes its degradation via the proteasome pathway. CRF6 interacts with JMJ15 and prevents its SnRK1a1 phosphorylation-dependent degradation, forming an antagonistic feedback loop. SnRK1a1, JMJ15, and CRF6 are required for transcriptional reprogramming in response to AA stress. The transcriptome profiles of jmj15 and crf6 mutants were highly correlated with those of plants overexpressing SnRK1a1 under both normal and AA stress conditions. Genetic analysis revealed that CRF6 acts downstream of SnRK1 and JMJ15. Our findings identify the SnRK1-JMJ15-CRF6 module that integrates energy and mitochondrial signaling for the growth-defense trade-off, highlighting an epigenetic mechanism underlying mitonuclear communication.

Mass spectrometry imaging (MSI) is an advanced analytical technique that combines mass spectrometry with spatial mapping, enabling the direct, label-free detection and visualization of molecular distributions within biological tissues. This review comprehensively outlines the fundamental principles, major technological platforms, and recent applications of MSI in plant science. We detail key ionization techniques - matrix-assisted laser desorption/ionization (MALDI), desorption electrospray ionization (DESI), and secondary ion mass spectrometry (SIMS) - focusing on their ionization mechanisms and instrumental characteristics. We then highlight the transformative impact of MSI in plant research, specifically covering: plant metabolomics, localization of bioactive compounds in medicinal plants, elucidation of plant-microbe interaction mechanisms, and studies of plant responses to environmental stresses. Finally, we discuss current challenges and future directions for the technology. Due to its high sensitivity, spatial resolution, and label-free capability, MSI has become a pivotal tool for uncovering plant physiological processes and metabolic regulatory networks, demonstrating significant potential for broad application in plant science.

Cotton (Gossypium spp.), a major global fiber crop, serves as an ideal model for research on plant cell development. According to the acid growth theory, plasma membrane (PM) H +-ATPase (HA) regulates cell wall acidification, thereby promoting cell elongation and providing a mechanistic framework for understanding this process. However, its application to cotton fiber cells has remained limited. In this study, the acid growth theory was utilized to investigate the elongation of cotton fibers. Comparative genomics revealed an expansion in the number of gene family members associated with acid growth, including PM HA and transmembrane kinase (TMK) genes, in tetraploid cotton. Transcriptomic analysis highlighted the co-expression of these genes during fiber elongation. Functional validation using chemical modulators and CRISPR-Cas9-mediated knockout mutants demonstrated that PM HA activity is essential for apoplastic acidification and fiber elongation. Specifically, GhHA4A and GhTMK3A were identified as potential regulators of proton extrusion; their loss-of-function mutants exhibited elevated apoplastic pH and reduced fiber length. Furthermore, the results indicated that an optimal apoplastic pH is required for fiber elongation, whereas insufficient or excessive acidification inhibits growth. Spatiotemporal modulation of PM HA activity in trans-genic cotton plants enhanced fiber length without affecting other fiber-and seed-related traits, demonstrating the potential of the acid growth theory for fiber improvement. These findings not only extend the acid growth theory beyond conventional model systems but also provide an innovative strategy for increasing fiber length in cotton breeding.

The root system architecture (RSA) determines plant growth and yield. The characterization of optimal RSA and discovery of genetic loci or candidate genes that control root traits are therefore important research goals. However, the hidden nature of the root system makes it difficult to perform nondestructive, rapid analyses of RSA. In this study, we developed an automated, nondestructive, high-throughput root phenotyping platform (Root-HTP) and a corresponding data processing pipeline for efficient, large-scale characterization of wheat (Triticum aestivum L.) RSA. This system is capable of tracking root growth dynamics and RSA variation across all wheat developmental stages. In situ phenotyping using Root-HTP extracted 47 RSA traits, including 33 novel traits in wheat and 23 novel traits in other crops. We used root trait data from the phenotyping system and yield trait data to conduct a genome-wide association study (GWAS) of 155 wheat accessions, which identified 2,650 SNPs and 233 quantitative trait loci (QTLs) associated with aspects of root architecture. The candidate gene TaMYB93 was detected in a QTL for root tortuosity, and EMS mutants confirmed its effect on RSA in wheat. We explored the relationship between root- and yield-related traits and identified 20 root-related QTLs that were also associated with yield traits. Furthermore, we have built a predictive model for wheat yield based on 18 RSA traits and propose a parsimonious RSA ideotype associated with high yields. The data generated from this study provide insight into the genetic architecture of wheat RSA and support for RSA ideotype-based wheat breeding and yield prediction.