Physiologia plantarum最新文献

In the Pooideae subfamily, resistance to insect herbivores often depends on a defensive mutualism with Epichloë fungal endophytes, which produce anti-invertebrate alkaloids such as lolines and peramine. Herbivory can induce alkaloid accumulation and enhance endophyte-conferred resistance, a response interpreted as analogous to classical herbivore-induced resistance in plants. Yet, abiotic stressors, particularly drought, also stimulate alkaloid production and resistance, suggesting a more general response linked to oxidative stress. Despite these insights, no quantitative synthesis exists, and the regulation of alkaloid induction under stress remains poorly understood. Using a meta-analysis, we synthesized published data to test whether herbivory or drought enhance Epichloë-mediated resistance and increase the in planta concentrations of lolines and peramine. Both stressors significantly elevated resistance, associated with higher alkaloid concentrations, particularly lolines. Peramine increased under drought but not consistently with herbivory. Published molecular and biochemical studies implicate oxidative stress, particularly changes in reactive oxygen species (ROS) levels, in regulating alkaloid production through precursor accumulation and fungal signaling pathways involving NADPH oxidases and stress-activated MAP kinases. Given that Epichloë enhances plant tolerance to stress and that ROS play a key role in the plant-endophyte communication, we propose that alkaloid induction and herbivore resistance are beneficial by-products of endophyte-mediated stress responses, rather than solely adaptive outcomes of coevolution with herbivores. This perspective highlights how herbivory and drought converge on oxidative stress pathways to modulate plant-endophyte associations, with implications for plant defense under climate-driven stress scenarios.

Lignin deposition in stone cells is critical for pear fruit quality. However, calcium ions (Ca²⁺) exert critical regulatory effects on fruit growth and development. Nevertheless, the molecular mechanisms underlying Ca²⁺-mediated stone cell formation in pear remain poorly characterized. Our study revealed that exogenous application of CaCl₂ decreased lignified stone cell formation in "Nanguoli" (Pyrus ussuriensis) fruits and significantly downregulated the expression of lignin biosynthesis-related genes laccase7 (PuLAC7) and peroxidase42 (PuPRX42). Transcriptome sequencing (RNA-seq) identified a transcription factor, PuMYB73, which was significantly inhibited by CaCl₂ in pear fruit stone cell formation and lignin accumulation. Yeast one-hybrid (Y1H) and β-glucuronidase (GUS) activity analysis revealed that PuMYB73 directly binds and activates lignin biosynthesis genes PuPRX42 and PuLAC7 promoters, thereby decreasing PuPRX42 and PuLAC7 expression after CaCl₂ treatment. Strikingly, PuMYB73 interacts with PuNAC21 to form a Ca²⁺-responsive module, lowering the transcription of PuPRX42 and PuLAC7 after Ca²⁺ treatment, which contributed to decreasing pear stone cell production. Collectively, exogenous CaCl₂ treatment inhibits stone cell and lignin biosynthesis in pears mediated by the PuMYB73-PuNAC21 regulatory module. Our results revealed that the Ca²⁺-PuMYB73-PuNAC21-PuLAC7/PuPRX42 regulatory module inhibits lignin biosynthesis, providing important insights into reducing stone cell content in pear via molecular breeding.

Plants in high latitude regions frequently experience cold stress, which strongly constrains plant growth and development. Although arbuscular mycorrhizal fungi (AMF) can form beneficial symbiotic relationships with plants, their role in mediating anatomical adaptations under different temperature regimes remains insufficiently understood. In this study, we investigated how inoculation with the AMF Funneliformis mosseae influences anatomical responses in Hordeum jubatum under contrasting temperature conditions using detailed microscopic analysis. Under normal temperature conditions, AMF inoculation promoted significant improvements in plant anatomical structures. Stomatal dimensions including length, width and area showed marked increases alongside elevated stomatal density. Leaf tissues exhibited enhanced development, particularly in vascular and epidermal components, while root systems displayed an expanded radius, greater cortical thickness and larger metaxylem area. These coordinated modifications demonstrated a comprehensive optimization throughout the root-leaf continuum. In contrast, under cold stress conditions, the positive effects of fungal inoculation were substantially diminished. Although a few traits, such as abaxial epidermal thickness and root cortical cell area, showed partial improvement, most anatomical parameters exhibited minimal responses to fungal treatments at low temperatures. This pronounced contrast between temperature regimes highlights the limited capacity of this single fungal strain to support anatomical adaptations under cold stress. These findings provide important insights into plant-microbe interactions under challenging environmental conditions and demonstrate that AMF-mediated benefits are strongly temperature dependent. Our work advances the understanding of the contextual nature of plant-AMF relationships and offers valuable anatomical perspectives for developing improved strategies to enhance plant resilience in cold-climate ecosystems.

As droughts become more common due to climate change, plant survival may rely not only on its immediate response but also on what it has learned from past challenges. However, we still know little about how plants integrate different types of experiences, such as recurrent drought and hormonal cues, from previous generations. In this study, we examined whether clonal offspring of a grass species, Festuca rubra, previously exposed to drought, stress hormone methyl jasmonate (MeJA), or their combination inherited biological memories that help them tolerate new drought stress. We combined untargeted LC-MS metabolomics with morpho-physiological measurements to evaluate these memory effects. We found that each type of memory changed plant metabolism and physiology, but the most notable changes occurred when both memories were present, and plants faced recurrent drought conditions again. This interaction between drought memory, MeJA memory, and current stress did not just add effects; it created entirely new metabolic responses, not seen in any single treatment. These combined memories fine-tuned water conservation, photosynthesis, and extensive metabolomic reshuffling, revealing a deeper level of drought resilience. Our results uncover a layered memory system in plants where past stresses do not act in isolation but interact to reshape future responses. This offers new insight into how plants prepare for stress and suggests practical strategies for priming drought tolerance across plant generations.

Drought events can have long-lasting effects on plant performance and progeny traits. We investigated how an early, severe drought at the seedling stage affected plant fitness and seed traits in Lolium multiflorum, and whether these responses were modulated by symbiosis with the vertically transmitted fungal endophyte Epichloë occultans. Drought caused significant mortality, and the symbiosis with the endophyte improved survival independently of plant biomass. Surviving plants fully recovered aboveground biomass and seed production only in the presence of the endophyte. Isotopic analyses indicated that only non-symbiotic plants showed reduced stomatal conductance during seed set, which likely explains their lower seed production. Seeds from drought-exposed symbiotic plants had higher concentrations of compatible solutes (mannitol and sorbitol) and starch. However, symbiotic seeds from drought-exposed plants showed reduced germination under intermediate water potential. This response was associated with a drought-induced increase in the base water potential (Ψ_b). Alternatively, constant hydrotime was positively associated with starch content. Our results suggest that endophyte symbiosis enables recovery from early drought via osmotic adjustment and photosynthetic maintenance, with intergenerational responses mediated by changes in seed biochemical composition and germination. These findings highlight the role of vertically transmitted endophytes in plant memory of stress and drought resilience across generations.

Polyploid plants often present a variety of agriculturally advantageous traits, such as larger organs. Plant cell expansion is ultimately constrained by the cell wall, yet the impact of polyploidization on the cell wall architecture of orchids remains unexplored. Here, we employed Dendrobium catenatum (syn. D. officinale) as a model to dissect the impacts of polyploidization on phenotypic traits, cell size and cell wall composition. Compared with diploids, tetraploids of D. catenatum have larger organs underpinned by larger cells. The analysis of gene expression revealed that the differentially expressed genes (DEGs) were significantly enriched in the cell wall metabolism and DNA packaging pathways. The cell wall component lignin- and xylan-related transcripts were upregulated, whereas histone-variant genes were repressed. Compositional assays revealed that the contents of many cell wall components, such as lignin, are increased in tetraploids. Despite cell wall reinforcement, tetraploids remained colonized by the symbiotic fungus Serendipita indica, although fungal biomass was moderately reduced. Thus, polyploidization enlarges D. catenatum by reprogramming cell wall construction, while preserving the plant's ability to maintain fungal symbiosis.

Receptor-like kinases (RLKs) detect external and internal signals, triggering responses essential for growth and adaptation. Among internal cues, cell wall integrity (CWI) sensing plays a key role, as changes in cell wall structure activate responses critical for development and defense. While RLKs are well-studied in vascular plants, their diversity and function remain largely unknown in green algae belonging to the Chlorophyta phylum, a group that is relevant for global oxygen production and carbon cycling. Due to their varied cell wall structures, Chlorophyta offer a useful system to study the origins of CWI sensing. In this study, we used advanced bioinformatics and AI-based tools to analyze RLKs in 34 Chlorophyta species, mapping their distribution, structural features, and similarity to plant RLKs. We identified 736 putative RLKs, expanding the known repertoire in green algae. Structural analyses showed a wide range of extracellular domains, including motifs related to plant CWI sensors: domains mediating protein interactions (e.g., Leucine Rich Repeats-LRR, Plasminogen Apple Nematod e-PAN, Armadillo repeat-ARM), cell wall remodeling (e.g., glycosyl hydrolases, lyases), and mechanosensing (e.g., Leucine-Proline-X-Threonine-Glycine motifs-LPXTG, Fibronectin). This diversity suggests that mechanisms for extracellular sensing and CWI monitoring emerged early in evolution. The results provide a basis for future studies on the function of RLKs in algae and their evolutionary links to vascular plant signaling.

Fruit quality in wampee is strongly influenced by the accumulation of key metabolites, including anthocyanins, sugars, and organic acids, yet their metabolic dynamics during fruit development remain poorly understood. In this study, we analyzed metabolite profiles and the expression of metabolism-related genes in the pulps of two wampee cultivars, "Jixin" (JX) and "Zirou" (ZR), across multiple fruit developmental stages. Two anthocyanins, 17 sugars, and 32 organic acids were identified. Total phenolics, flavonoids, starch, and soluble sugars accumulated mainly during early fruit development. "JX" wampee exhibited higher ascorbic acid levels than "ZR" wampee. Sucrose and citric acid were the predominant sugars and organic acids in both cultivars. Transcriptomic analysis revealed 37 anthocyanin-related, 29 sugar-related, and 18 organic acid-related genes. Strong correlations between candidate gene expression and metabolite levels suggest that these genes play key roles in regulating the biosynthesis and accumulation of anthocyanins, sugars, and organic acids in wampee.

Rose represents the most traded cut flowers worldwide with enormous diversity in floral organs, especially petal number, a target trait during modern rose breeding. With a detailed phenome analysis, we here report the high variation pattern in floral organ number among 132 rose lines, including wild species, traditional Chinese varieties, and modern lines. Seven wild species are single- or five-petaled flowers. Intriguingly, compared to traditional Chinese roses, modern lines feature more floral organs in the inner three whorls simultaneously (about 36% more total floral organs), a pattern that has not been identified previously. More floral organs correlate with the increase of flower meristem size, a pattern tightly controlled by the CLAVATA3 (CLV3) and its related molecular module in known model species. Within the vicinity of a known petal number QTL, in which polymorphism in APETALA2 (AP2) has been hypothesized to regulate the rose double flower trait, we identified the presence of CLV3, whose expression domain conversely correlates with total floral organ numbers in roses. Genetic alteration of CLV3 expression in both rose and Arabidopsis significantly altered the meristem size and the floral organ development and number. Exogenous application of rose CLV3-encoded CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptide led to reduced meristem size, accompanied by reduced root length in both rose and Arabidopsis plants. Collectively, our data suggest that, either alone or working potentially together with the AP2 variation, expression diversity in CLV3 may serve as an important factor regulating floral organ number diversity in roses. These findings thus provide fresh insights into the molecular mechanisms underlying the floral organ number trait in both roses and other ornamental plants.

Blockage of xylem vessels can compromise water flow in trees, eventually leading to reduced gas exchange and productivity. The extent of these impairments also depends on how effectively blocked vessels can be bypassed through lateral pathways. We hypothesize that the ability to bypass can vary crucially between different species of the same clade, leading to differences in the hydraulic limitations after a defined loss of conducting vessels. Here, we test this hypothesis on 1-year-old seedlings of two Mediterranean angiosperm tree species, carob (Ceratonia siliqua) and oak (Quercus calliprinos). We consecutively notched stems to artificially block water flow through vessels in one half of the cross-section. We measured the effect of notching on leaf gas exchange and visualized altered water flow pathways using microscopy and μCT imaging. In carobs, stomatal conductance (g_s) of leaves on the notched side decreased by more than 90%. Water transport in the notched side of the stem had ceased. In oaks, leaves on the notched side maintained more than 50% of their g_s with no signs of dehydration. Microscopy and μCT imaging revealed that water supply to these leaves occurred through lateral pathways outside vessels. This can be explained by the presence of tangentially oriented arrays of tracheids with bordered pits, which we found in oaks but not carobs. Our study emphasizes the importance of non-vessel water flow in angiosperm trees when the xylem becomes partially blocked.