Physiologia plantarum最新文献

Powdery mildew (PM) is one of the major diseases in pumpkin cultivation. However, the molecular mechanism of epigenetic regulation in pumpkin defense against PM is still unclear. This study integrated physiological, methylome, and transcriptome analyses of Cucurbita moschata leaves infected with Phytophthora xanthii. PM infection significantly increased the MDA content and CAT, POD, and SOD activities in pumpkin leaves, while reducing protein and chlorophyll content. Global DNA methylation decreased in P. xanthii-infected plants, with prominent hypomethylation at CHH contexts in promoter regions. The analysis of methylome and transcriptome identified 2668 differentially methylated genes (DMGs) and 2356 differentially expressed genes (DEGs), respectively. GO functional annotation and KEGG pathway enrichment analyses revealed that DMGs and DEGs were primarily involved in antioxidant, photosynthesis, and metabolism. A correlation analysis between promoter DNA methylation level and gene expression identified 160 negatively correlated genes, which included members involved in photosynthesis, lipid metabolism, antioxidant responses, transcription factors, and methyltransferases. We further confirmed the function of CmERF098 as a nuclear transcription factor. RT-qPCR analysis revealed that the CmERF098 gene responds to both PM stress and MeJA treatment. In C. moschata, overexpression of CmERF098 conferred resistance to PM by reducing MDA content while enhancing POD activity as well as chlorophyll and protein content. Additionally, overexpression of CmERF098 suppressed the JA signaling pathway via downregulation of CmMYC2 and CmJAR1. These findings provide novel insights into the molecular mechanisms underlying epigenetic regulation and provide new candidates to incorporate in breeding for disease-resistant pumpkins.

Drought is one of the most critical abiotic stresses limiting global crop productivity, and nanoparticles (NPs) have recently emerged as promising tools to enhance plant stress tolerance. However, how strongly and in what ways NPs influence plant performance is not yet well established, particularly in relation to drought intensity and nanoparticle identity. We conducted a comprehensive meta-analysis of studies assessing physiological and biochemical traits, comparing plant responses with and without nanoparticle application under well-watered, moderate, and severe drought conditions, and identifying particle-specific effects through subgroup analyses. The results revealed that application of NPs consistently improved plant performance in a stress-dependent manner. Chlorophyll content effect size increased up to 44% under moderate drought, while oxidative stress markers (MDA, H₂O₂) declined more than twofold under both moderate and severe drought. Under severe drought, nanoparticles markedly enhanced antioxidant activities: CAT, SOD, and POD effect size increased by about 30%-35% relative to controls. Particle-specific responses evidenced that titanium NPs produced the highest yield gains (effect size = 11.1), whereas iron-based NPs had negligible effects. Under well-watered conditions, titanium, zinc, and silicon-based NPs promoted chlorophyll accumulation and yield stability. Under moderate drought, zinc, silicon, and selenium-based NPs improved yield and pigments, while titanium NPs supported osmotic balance. Under severe drought, copper, cerium, and titanium-based NPs showed strong osmotic and enzymatic protection. Overall, this meta-analysis shows that NPs improved plant performance across both optimal and drought conditions, with responses varying according to drought severity and nanoparticle identity.

Elevated temperatures severely disrupt pollen function, posing a major threat to agricultural productivity. While research into pollen thermotolerance is rapidly expanding, the quest to identify and develop heat-tolerant crops is challenged by a lack of consistent methodological considerations and experimental design principles. This review critically examines the experimental pipeline for assessing pollen quality and function under heat stress conditions, pinpointing where methodological variability most affects data reliability and comparability. We emphasize that accurate assessment begins with a careful experimental design, including the selection of appropriate methods to test thermotolerance, precise staging of pollen development, and effective sampling strategies to ensure comparable pollen populations. We then detail how different thermal stress parameters, such as duration, intensity, and timing, should be appropriately applied to accurately capture physiological responses, including the induction of thermotolerance. Finally, we provide a structured overview of current phenotypic and molecular assays, emphasizing the importance of high-throughput techniques in uncovering underlying mechanisms of pollen thermotolerance. By offering clear guidance and recommendations at each stage, from experimental setup to data analysis, this review offers a consistent and rigorous approach to pollen heat stress studies, aiming at enhancing the reproducibility and impact of future discoveries in this vital field.

The labellum, a distinctive floral organ unique to orchids, possesses significant ornamental and research value. Here, wild type plants (W1, W2), a lip-like sepal mutant (MS), a lip-like petal mutant (MP), and a peloric flower mutant (ML) of Cymbidium ensifolium were used to elucidate the molecular mechanisms underlying labellum formation. Morphological and cytological analyses revealed that MS sepals and MP petals acquired labellum-like traits (folded structures, conical papillae), whereas ML labella adopted petal-like features (flat epidermal cells). Transcriptome analysis identified seven key B- and E-class MADS-box genes (including DEF-/AP3-, SEP-, and AGL6-like genes) potentially involved in labellum development. Subsequent qRT-PCR profiling showed that gene expression dynamics closely reflect organ fate. Expression of CeAP3-3 and CeAP3-4 correlated with the establishment of inner perianth identity (petal/labellum), while CeAGL6-2 activation was specifically associated with labellum specification. Notably, CeAGL6-2 was ectopically expressed in lip-like organs of MS and MP, but absent in the petaloid labellum of ML. Conversely, expression patterns of CeAP3-1 and CeAGL6-1 suggested roles in promoting sepal/petal or non-labellum perianth fates. Protein interaction assays (Y2H, BiFC) demonstrated that CeAP3-3 interacted strongly with CeAGL6-2 and CeSEP2, while CeAP3-4 interacted with CeSEP2. Integrating these results, we propose a model in which heteromeric complexes formed by CeAP3-3, CeAGL6-2, and CeSEP2 are central to specifying labellum identity in C. ensifolium. Overall, these findings highlight the cooperative role of B- and E-class transcription factors in labellum specification through dynamic expression shifts and protein interaction networks, thereby enriching our understanding of the molecular mechanisms driving orchid labellum formation.

Experimental evidence on the antioxidant role of arbutin, the main phenolic constituent in pear trees, remains limited. In this study, we investigated the effect of exogenous arbutin on the resistance of pear leaves to methyl viologen (MV)-induced oxidative stress. The results showed that arbutin application alleviated chlorophyll degradation and maintained higher photosynthetic efficiency under MV stress. Exogenous arbutin also attenuated the accumulation of malondialdehyde and H₂O₂ and promoted the activity of antioxidant enzymes. Additionally, exogenous arbutin had a mitigating effect on the MV-induced decline in phenolic accumulation and antioxidant capacity, as demonstrated by DPPH and FRAP assays. The expression of phenolic and arbutin biosynthesis-related genes (PAL, CHS, and UGT) significantly increased after MV exposure. Furthermore, arbutin-pretreated pear calli exhibited enhanced tolerance to cold, salt, and abscisic acid (ABA) stresses, characterized by elevated antioxidant enzyme activity and decreased oxidant levels. In tobacco leaves, transient overexpression of UGT enhanced arbutin accumulation and alleviated MV-induced oxidative damage. Collectively, these findings highlight the function of arbutin in controlling oxidative stress responses in pear leaves.

Ultraviolet-B (UV-B) radiation is an intrinsic component of the solar spectrum that acts as an environmental cue, exerting a strong influence on plant physiology, morphology, and environmental acclimation. UV RESISTANCE LOCUS 8 (UVR8) is recognized as the sole specific UV-B photoreceptor, mediating perception and initiating a sophisticated signaling cascade that facilitates developmental and protective responses. UV-B irradiation triggers the dissociation of the cytosolic UVR8 homodimer into biologically active monomers. This structural transition enables rapid, regulated nuclear translocation, where the UVR8 monomer interacts with the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). This interaction, involving a critical two-interface binding mechanism, inhibits COP1 activity toward key transcription factors, notably ELONGATED HYPOCOTYL 5 (HY5), thereby stabilizing them and orchestrating the UV-B acclimation transcriptome. Furthermore, UVR8 functions as a crucial hub for signaling integration, directly modulating multiple phytohormone pathways, coordinating spectral responses with other photoreceptors, and regulating novel non-canonical modules in both the nucleus and the cytoplasm. This comprehensive review examines the molecular architecture, photocycle dynamics, integrated signaling mechanisms, and critical physiological roles of UVR8. Finally, we provide perspectives on unresolved questions concerning its full array of post-translational modifications and the potential to apply this knowledge to enhance crop resilience.

The increasing frequency of abiotic and biotic stresses, such as drought, salinity, high temperatures, and pathogen attacks, threatens global agricultural productivity and food security. To address this, applying stimulants through foliar sprays has become a promising, sustainable method to boost plant resistance and improve crop yields. This review discusses the mechanisms, applications, and effects of using foliar stimulants, including amino acids, humic substances, phytohormones, vitamins, micronutrients, and plant extracts. Foliar application allows rapid nutrient absorption through stomatal openings and the cuticle, resulting in systemic movement via both apoplastic and symplastic pathways. Once absorbed, these stimulants activate physiological and biochemical processes, including hormonal regulation, antioxidant enzyme activity, osmolyte production, and stress-related gene expression. These processes collectively help maintain chlorophyll levels, enhance photosynthesis, strengthen cellular structures, and increase resistance to environmental stresses. Under abiotic stress, foliar applications of seaweed extracts, salicylic acid, silicon, and melatonin help stabilize membranes, improve water use efficiency, and preserve chlorophyll pigments. In cases of biotic stress, foliar stimulants support defense signaling, inhibit pathogen growth, and reduce visible disease symptoms like necrosis, and wilting. The review highlights how foliar application of stimulants contributes to sustainable agriculture by providing an eco-friendly alternative to traditional agrochemicals, improving nutrient use efficiency, and increasing crop yields even under adverse conditions. Furthermore, this review summarizes the recent advances in foliar stimulant research, providing a comprehensive framework for understanding their diverse roles and offering new perspectives on their practical applications in sustainable crop management.

Leaves maintain a pool of non-structural carbohydrates (NSC) whose size can vary over hourly and longer timescales. We tested two long-standing hypotheses regarding potential physiological roles of changes in foliar NSC levels. The first is that soluble NSC plays a critical role in osmotic adjustment, with their increase enabling stomatal opening despite daily and seasonal reductions in leaf water potential (Ψ_leaf). The second is that increases in NSC are a sign of excess assimilation relative to sink demand and serve as a signal to downregulate gas exchange. To explore these questions, we monitored the diurnal and seasonal dynamics of gas exchange, Ψ_leaf, osmotic potential, and NSC of irrigated and dehydrated grapevines (Vitis vinifera) through two consecutive growing seasons. We found that the daily accumulation of soluble sugars constitutes approximately 50% of the daily osmotic adjustment (0.2 MPa), enabling the vines to maintain turgor under low Ψ_leaf. At the same time, the importance of NSC as osmolytes decreased as the season progressed, and they did not contribute to osmotic adjustments when water was withheld. Additionally, there was no negative correlation between NSC and gas exchange, implying that bulk NSC concentration is not the signal for photosynthetic feedback inhibition.

Abiotic stresses, such as drought, salinity, and extreme temperatures, have profound effects on plant reproduction, often leading to reduced fertility and yield. Reproduction in plants involves complex interactions between diverse cells, necessitating spatiotemporal resolution to understand how stress impacts each component of this intricate system. Imaging techniques have emerged as indispensable tools for uncovering the cellular and molecular responses of reproductive tissues to abiotic stresses in Arabidopsis and crops. Advanced methods, including fluorescence-based dyes and genetically encoded biosensors, have enabled the visualization of key stress-associated molecules such as reactive oxygen species and calcium ions. These approaches reveal the dynamic and localized nature of stress responses. Additionally, state-of-the-art imaging technologies, including light-sheet microscopy, structured illumination (e.g., Apotome), high-content confocal microscopy, micro-computed tomography, and custom heated-stage setups, provide varying levels of spatial and temporal resolution to study stress-induced changes in tissue morphology and development. Complementary techniques like sectioning and staining continue to yield critical insights into the anatomical and developmental alterations under stress conditions. This review integrates findings from these methodologies, highlighting their contributions to our understanding of abiotic stress responses in male and female reproductive tissues. Furthermore, we identify technological advancements needed to enable real-time, (sub)cellular-level imaging of stress responses. Finally, we compile a list of promoter-based identity markers specific to reproductive tissues across different crop species, offering a resource for targeted genetic studies. By bridging current imaging techniques with biological insights and technological gaps, this work aims to advance the field of plant stress biology and reproductive resilience.

Chrysanthemum white rust (CWR), caused by Puccinia horiana Henn., has been a significant obstacle for chrysanthemum growers, impacting both the ornamental and monetary value of the plant. Tapping disease resistance genes and breeding new disease-resistant cultivars are therefore essential. Our previous study identified CmPAL as a differentially expressed gene in response to CWR from the transcriptome database. However, the molecular mechanism of its response to P. horiana infection remains unclear. Here, CmPAL was identified from the chrysanthemum resistant cultivar "C029," and its expression was strongly activated with P. horiana infection. We found that CmPAL positively regulated resistance to P. horiana. Silencing of CmPAL in "C029" resulted in an increased spore load on leaves. Conversely, overexpression of CmPAL reduced the spore growth rates and enhanced resistance to CWR after inoculating P. horiana. In addition, overexpression of CmPAL in susceptible cultivar "Jinba" promoted the synthesis of SA and lignin and activated the expression of SA pathway genes (CmPRs and CmNPR1) and lignin pathway genes (CmCAD and CmC4H). The opposite effects were observed in the silenced lines. The promoter sequence of CmPAL was found to contain a conserved W-box cis-element. We further identified that CmWRKY15-1 binds directly to the W-box cis-element in the CmPAL promoter. Based on our results, we demonstrated that CmPAL plays a critical role in chrysanthemum resistance to CWR by promoting SA and lignin synthesis.