Physiologia plantarum最新文献

Tetrastigma hemsleyanum Diels et Gilg (T. hemsleyanum) is a plant of considerable medicinal and economic value. However, the molecular mechanisms underlying its tuberous root formation remain poorly understood. To investigate the molecular basis of tuberous root formation, we analyzed hormonal metabolic levels, transcriptomic profiles, and root anatomical changes during this process. Using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry, we quantitatively assessed the levels of eight plant hormones and their derivatives in the early stages of tuberous root formation and in adventitious roots. The results revealed significant fluctuations in hormone levels, with a marked upregulation of cytokinins (tZ, DZ, and IP) and the complete absence of gibberellin GA₁ post-tuberous root formation. Jasmonic acid content decreased, while methyl jasmonate (MeJA) increased substantially. Exogenous application of MeJA further confirmed the role of the jasmonic acid pathway in tuberous root formation, underscoring the pivotal role of these hormones in root differentiation and expansion. Additionally, transcriptomic analysis identified significant alterations in biological processes associated with the cytoskeleton and cell wall during tuberous root formation. Anatomical observations indicated reduced lignification and a notable increase in vascular cambium and xylem parenchyma cells. In conclusion, this study provides valuable insights into the molecular mechanisms of tuberous root formation in T. hemsleyanum, emphasizing the critical role of plant hormones and offering new strategies for enhancing tuber growth and yield through hormonal regulation.

The ubiquitin-proteasomal protein degradation system is a key regulatory process mediating the dehydration stress response in plants, and RGLG proteins, a subfamily of the RING E3 ligases, are well known to modulate this response. In this study, we isolated four SlRGLG proteins (Solanum lycopersicum RING domain ligase) from tomato plants and characterized their functions at the molecular and biological levels. We found that these four SlRGLGs have the conserved VWA and RING domains and high amino acid sequence identities with RGLGs from Arabidopsis thaliana and pepper plants. The transcript levels of SlRGLGs were found to be responsive to several environmental stimuli, including dehydration, mannitol, and abscisic acid, which are believed to be associated with the presence of different stress-associated cis-regulatory elements in the respective promoter regions. Subcellular localization studies of SlRGLGs-GFP fusion proteins revealed distinct subcellular distribution patterns, and all four MBP-SlRGLGs recombinant proteins exhibited robust E3 ligase activities in vitro. To elucidate their biological roles in the dehydration stress response, we generated SlRGLGs-silenced tomato plants and SlRGLGs-overexpressing (OE) Arabidopsis plants. Notably, all SlRGLGs-silenced tomato plants were found to have dehydration-sensitive phenotypes with increased transpirational water loss and lipid peroxidation of cell membranes and decreased expression of dehydration stress-responsive genes. However, all SlRGLGs-OE Arabidopsis plants showed the dehydration-tolerant phenotypes, compared to control plants. Collectively, these findings indicate a positive role for all four SlRGLGs in the dehydration stress response of tomato.

Phosphorus (P) deficiency and water deficit are major constraints to soybean yield worldwide. While their individual impacts are well established, little is known about how P deficiency modulates soybean recovery from recurrent water stress. This study evaluated the effects of P deficiency on the recovery capacity of two soybean cultivars, contrasting in drought sensitivity, during the grain-filling stage. Plants were grown under either high P availability or P deficiency and subjected to different irrigation regimes: well-watered (WW), severe water deficit at R5 (WS-R5), and moderate deficit at V5 followed by severe deficit at R5 (WS-V5 + R5). The experiment followed a randomized complete block design in a 2 × 3 factorial scheme. Under water stress, P deficiency delayed stomatal resistance, extending photosynthetic decline in both cultivars. However, recovery of photosynthetic rate and stomatal conductance was faster under P deficiency than under high P supply. In the sensitive cultivar, P deficiency enhanced memory-mediated recovery of photosynthesis only after two stress cycles, with compensatory increases in mesophyll conductance, decreasing mesophyll limitations and favoring recovery. In contrast, the tolerant cultivar showed stable photosynthetic responses regardless of P level, with similar recovery in light saturation and photorespiration. Grain composition was affected by P deficiency in both cultivars, with lower protein concentration and increased oil content, particularly of unsaturated fatty acids. These results indicate that P deficiency alters physiological adjustments in soybean genotypes sensitive to water deficit, influencing their capacity to recover from recurrent drought stress and affecting grain quality.

Moso bamboo (Phyllostachys pubescens), a fast-growing and potentially invasive species, exhibits culm-age heterogeneity in structure and physiology; however, its water-use strategies in relation to aging remain unclear. Thus, we aimed to examine age-related variations in hydraulic performance, vessel integrity, and nutrient allocation in bamboo culms aged 1-5 years. Sap flux density peaked in 2-year-old culms, possibly reflecting the maturation of conductive tissues. However, daily sap flow rates showed no significant age-dependent differences. Dye tracing and cryo-scanning electron microscopy revealed consistent axial and radial vessel continuity and low embolism frequency across all age groups, with a relative loss of potential conductivity of approximately 10%. Elemental analysis showed reduced K concentration and delayed Si accumulation in the vessel sap with age, suggesting a physiological shift from osmotic regulation to structural reinforcement. Starch began accumulating in the third year and peaked at age four, indicating a physiological transition from resource consumption to energy storage. These coordinated transitions support sustained water transport across ages and may enhance resilience under drought and interspecific competition. Our findings revealed functional plasticity in water use and resource allocation during culm development, highlighting the physiological mechanisms that may underlie the ecological success and invasive potential of Moso bamboo.

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.

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.

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.