Plant, Cell & Environment最新文献

The phyllosphere encompasses all above-ground plant parts, covering ~10⁹ km² and hosting as many as 10²⁶ microbial cells, yet its chemical ecology remains understudied compared to the rhizosphere. This review synthesizes recent advances in metabolite-mediated communication orchestrating phyllosphere microbiome assembly, function and host feedback. Leaf structural traits, host immune genes, developmental stage, and fluctuating environmental drivers create spatiotemporal chemical niches that filter incoming microbes. We then examine four major classes of plant-derived signals, including primary metabolites, secondary metabolites and phytohormones, with an emphasis on their dual functionality. Microbial feedback occurs through phytohormone synthesis/catabolism, volatile and soluble effectors and antimicrobial metabolites that collectively modulate plant immunity, growth and stress tolerance while structuring inter-microbial competition. These bidirectional exchanges form a dynamic network where plants and microbes continuously negotiate cooperation and conflict under diurnal and seasonal oscillations. We outline translational prospects, including probiotic foliar applications, metabolite priming and breeding for beneficial consortia, while identifying key challenges in signal attribution, microbiota stabilization and deciphering community-level crosstalk dynamics for sustainable crop protection.

Microbial fortification represents a promising approach for selenium biofortification in crops. Building on the previous discovery that Bacillus cereus SESY enhances selenium uptake in Brassica napus, this study employed an integrated multi-omics approach to investigate the mechanism by which B. cereus SESY enhances Se bioavailability in the Brassica napus rhizosphere. Inoculation with B. cereus SESY significantly increased selenium content in Brassica napus roots and shoots in calcareous soil by 42.9% and 21.5%, respectively, and increased the selenium content of shoots in yellow brown soil by 30.7%. B. cereus SESY promoted the transformation of residual Se into bioavailable forms and enriched bacterial taxa with high motility and Se-transforming capacity (e.g., Lysobacter, Rhodanobacter, Sphingomonas and Burkholderiaceae) in rhizosphere soil. Key genes of these bacteria involved in Se metabolism (e.g., trxA, narH, cysE, cysK, metB) and cell motility genes (e.g., FlgG, CheW, FliH) were up-regulated. Core rhizosphere metabolites such as N-formylmethionine and xanthine correlated strongly with enriched bacteria abundance and available Se. Joint application of these metabolites with enriched bacteria increased plant Se content by 144% and rhizosphere soil available Se by 13.4%. These results reveal a metabolite-mediated microbial network that enhances Se mobility and plant uptake, providing a novel strategy for microbiome-driven biofortification.

The development of commercially available porometers has allowed for higher throughput measurement of stomatal conductance, but a body of evidence has suggested a persistent positive bias in their measurements relative to "reference" measurements from instrumentation based on infra-red gas analysis. We compiled a data set comprised of 25 angiosperm species, across a range of field conditions and found that the LI-COR LI-600, an open flow-through porometer, produced an exponentially increasing bias relative to the LI-COR LI-6800 infra-red gas analyser-based instrument in response to increasing stomatal conductance and decreasing relative humidity. This bias was minimal at lower stomatal conductance (below roughly 0.25 mol m ${}^{-2}$ s ${}^{-1}$ ), but was pronounced for larger values. We hypothesised that this bias is the result of the assumption of a constant air temperature throughout the flow stream used by the instrument software to estimate stomatal conductance from raw sensor measurements. We relaxed this assumption, and applied psychrometrics to augment the typical gas exchange equations with an additional energy balance constraint to solve for the temperature change throughout the air flow stream. We found that including this temperature difference corrects the computed transpiration and stomatal conductance values, and brings the porometer measurement into agreement with that of the infra-red gas analysis-based system. Software is provided to apply the correction to LI-600 output files. For future instrument design iterations, explicit measurement of temperature variation in the flow stream provides a potential opportunity for improvement in measurement accuracy at high stomatal conductance.

Insect-derived molecular cues can prime plant defences against herbivore attack. The genes that are sensitive to priming, and how their expression changes on the scale of days, have not been fully resolved. Moreover, priming may affect interactions with insects that are not the source of the priming cue. We primed tall goldenrod (Solidago altissima) plants by exposure to the volatile emission of a specialist herbivore, the goldenrod gall fly (Eurosta solidaginis) then subjected the plants to 48 h of herbivory from an unrelated generalist, corn earworm (Helicoverpa zea). Using RNA sequencing, we identified transcriptome-wide gene expression patterns between exposed and unexposed plants. We identified biotic stress-associated genes that were more abundant during herbivory in primed plants, including defence-related transcription factors, thaumatin-like receptors and chitinases. We observed a surprising rise and fall in expression of hundreds of defence-related genes in a 48-h phase in primed damaged plants only. Our results support the hypothesis that primed defences are stronger than typical induced defences and suggest that primed defences target herbivores in the short term. We show that the threat cue from a specialist can affect plant defences against an unrelated herbivore.

Tartary buckwheat, valued for its nutritious and medicinal quercetin. Following two independent domestication events, distinct quercetin accumulation patterns have emerged between the southwestern (SL) and northern (NL) landrace populations. However, the genetic mechanisms underlying these metabolic divergences remain elusive. Here, we identified the transcription factor FtNAC2 through genome-wide association study (GWAS) of quercetin content in 480 accessions of Tartary buckwheat. Haplotype analysis identified two single nucleotide polymorphisms (SNPs) in the FtNAC2 promoter that defined three major haplotypes, with higher promoter activity and gene expression observed in Hap2. Functional characterization revealed that FtNAC2 promotes quercetin accumulation in Tartary buckwheat hairy roots and potentially serves as a multifunctional regulator influencing both drought tolerance in buckwheat and seed size in Arabidopsis. Transcriptome co-clustering and pull-down mass spectrometry (MS) indicated FtNAC52 as a potential regulatory partner of FtNAC2. DNA affinity purification sequencing (DAP-seq) and quantitative reverse transcription PCR (qRT-PCR) analyses demonstrated that FtNAC2 promoted quercetin biosynthesis by upregulating FtF3'H and FtF3'5'H genes. Collectively, our results elucidated how FtNAC2 influences quercetin content variation in Tartary buckwheat, providing molecular insights into the differential quercetin accumulation between cultivated populations.

OsAAI1 belongs to the HPS_like subfamily of the AAI_LTSS superfamily, yet the molecular mechanism by which it regulates root development under osmotic stress remains unclear. In this study, we found that overexpressing OsAAI1 significantly promoted rice root system growth. Specifically, the primary root length, lateral root number, lateral root density and adventitious root count in the overexpression line (OE19) markedly exceeded those in the wild type (ZH11) and the osaai1 mutant. Consistent with this phenotypic enhancement, the root IAA content in OE19 was substantially higher than in ZH11 and osaai1. We further demonstrated that exogenous IAA application compensated for the root growth defects in the osaai1 mutant. Under PEG-induced osmotic stress, OE19 exhibited the most extensive and densely distributed root system, and exogenous IAA also rescued the inhibited growth of the osaai1 mutant. Mechanistically, we identified an interaction between OsAAI1 and the MADS-box transcription factor OsMADS25. This interaction enhanced the transcriptional expression of two key osmotic stress tolerance genes, LAX1 and OsBAG4. Furthermore, it upregulated the auxin biosynthesis gene OsYUC4 while suppressing the auxin inhibitory factor OsIAA14. This coordinated gene regulation promotes the auxin signalling pathway, thereby stimulating root growth and enhancing osmotic stress tolerance. Collectively, our findings indicate that OsAAI1 and OsMADS25 fulfil critical functions in rice osmotic acclimation by orchestrating downstream gene expression and modulating the auxin pathway.

Leaf spot disease, caused by the fungal pathogen Alternaria alternata f. sp. mali, poses a severe threat to apple production. Pathogenesis-related (PR) genes are crucial for plant immunity, yet their regulatory networks remain poorly understood. Here, we report that MdDREB2A, a transcription factor known for its role in abiotic stress, negatively regulates apple resistance to A. alternata by suppressing the expression of MdPR10 genes. We demonstrated that MdDREB2A overexpression plants exhibited increased susceptibility to A. alternata infection, whereas its knockdown conferred enhanced resistance. Based on DAP-seq analysis, we identified three MdPR10 genes as direct targets of MdDREB2A. This direct repression was confirmed by ChIP-qPCR, EMSA, and dual-luciferase assays, which showed that MdDREB2A binds to the promoters of MdPR10s to inhibit their transcription upon pathogen infection. Furthermore, functional studies revealed that MdPR10 proteins possess antifungal activity, and their overexpression enhanced resistance in apple leaves. Consequently, in MdDREB2A overexpression plants, the suppression of MdPR10s leads to diminished antifungal resistance. This study establishes MdDREB2A as a negative regulator of defense against A. alternata in apple, which operates by repressing the expression of three pathogenesis-related genes, thereby proposing a new strategic direction for developing resistant apple cultivars.

Chilling is an important abiotic stressor that significantly affects cucumber production. Melatonin (MT) modulates chilling responses by interacting with multiple signalling molecules; however, the molecular link between MT and nitric oxide (NO) in cucumbers under chilling stress remains elusive. Herein, we found prolonged chilling stress induced the accumulation of endogenous NO, whereas overexpression of MT biosynthesis gene N-acetylserotonin methyltransferase (CsASMT), with higher endogenous MT content, significantly increased chilling tolerance of cucumbers with decreased accumulation of NO via upregulation of the relative expression of S-nitrosoglutathione reductase gene (CsGSNOR), accompanied by decreased membrane lipid peroxidation and reactive oxygen species (ROS) accumulation. Moreover, we identified a transcription factor zinc finger of Cucumis sativus 10 (CsZAT10), and found CsZAT10 could directly bind to the promoter of CsGSNOR. Furthermore, we found CsZAT10 overexpression enhanced cucumber chilling resistance by directly activating CsGSNOR expression to mediate NO homoeostasis, whereas the suppression of CsZAT10 obviously decreased the chilling tolerance and CsGSNOR expression in cucumber induced by MT. Overall, our results demonstrate that MT enhances chilling tolerance in cucumber by regulating the CsZAT10-CsGSNOR-NO module.

Cadmium (Cd) is a toxic metal that accumulates in plants to inhibit growth and enters the food chain to harm human health. Although Cd accumulation and tolerance in plants have been extensively analysed, their regulation is less understood. Here, we identify a stress-responsive receptor-like kinase (OsSRK) involved in rice Cd accumulation and tolerance. Our results show that OsSRK expression was strongly induced by Cd treatment. OsSRK overexpression decreased while its silencing or mutations increased both Cd accumulation and Cd-induced leaf chlorosis in rice. OsSRK is a close homologue of MULTIPLE SPOROCYTE 1 (MSP1), which controls sporogenic development with its TAPETUM DETERMINANT1 (TPD1)-LIKE 1 A (OsTDL1A) ligand. OsSRK interacts with OsTDL1B, an OsTDL1A homologue, in both yeast and plant cells. Like OsSRK, expression of OsTDL1B was induced by Cd treatment, and mutations of OsTDL1B enhanced both Cd accumulation and Cd-induced symptoms in rice. These results strongly support that OsTDL1B acts as a ligand for the OsSRK receptor kinase in Cd stress signalling. Comparative transcriptome and proteome profiling support that OsSRK plays a critical role in rice Cd accumulation and tolerance through the regulation of genes in Cd accumulation and oxidative stress responses.

As plants grow taller, increasing conductive pathlength imposes hydraulic resistance, challenging the maintenance of water transport to leaves. While tip-to-base conduit widening along the stem helps mitigate this resistance, theoretical models and empirical data suggest that stem widening alone is insufficient to fully compensate. Here, we explore whether leaf length could contribute to maintaining hydraulic conductance by influencing vessel diameters in the stem. Across a diverse set of angiosperm species, we found that leaf length strongly predicts vessel diameter at the petiole base, and that petiole vessel diameter, in turn, scales positively with vessel diameter at the twig tip. These relationships imply that longer leaves are associated with wider conduits in the stem, potentially boosting stem-wide permeability. Simple fluid dynamic models show that the steep rate of conduit widening in angiosperm leaves plausibly buffers the resistance costs of increased leaf length. Because vessel diameter scales with the fourth power of conductance, modest increases in leaf length, and thus stem conduits, could lower the resistance not buffered by conduit widening in the stem. Leaf length during height growth may serve as a key mechanism in maintaining hydraulic supply, complementing conduit widening in the stem.