生命科学最新文献

Plants employ cell-type-specific transcriptional programs to defend against pathogens, yet the cellular heterogeneity of immune responses in the medicinal orchid Dendrobium officinale Kimura et Migo remains largely unexplored. A single-cell transcriptomic atlas of the D. officinale stem base upon Sclerotium rolfsii infection was constructed, profiling over 20 000 cells across 12 and 24 h post-infection. A total of 21 cell clusters were resolved into 6 major cell types-epidermal, ground tissue parenchyma, proliferating, xylem, phloem, and vascular bundle parenchyma cells-with identities validated by fluorescence in situ hybridization. Cell-type-specific analyses revealed that epidermal and phloem cells mounted early defense responses, while xylem cells exhibited the most extensive transcriptional reprogramming at 24 hpi, coinciding with the activation of lignin biosynthesis pathways. WRKY33 was identified as a central transcriptional activator that directly binds W-box motifs in the promoters of lignin biosynthetic genes C4H and HCT, promoting lignin deposition and enhancing disease resistance. Conversely, the nuclear-localized chaperone HSP81 physically interacts with WRKY33 and functions as a broad regulator of multiple transcription factors via co-factor sequestration, thereby compromising defense when overexpressed. These findings uncover a WRKY33-HSP81 regulatory module that orchestrates phenylpropanoid-mediated defense in D. officinale, providing a high-resolution cellular framework for understanding plant immunity and offering potential targets for improving disease resistance in this economically valuable species.

Seed dormancy is a complex developmental and agronomic trait requiring a delicate balance: insufficient dormancy leads to pre-harvest sprouting (PHS), while excessive dormancy causes uneven germination. Understanding the intrinsic mechanisms resolving this trade-off is vital for crop improvement. In this study, our findings indicate that the heat shock transcription factor OsHsfA2a acts as a negative regulator of seed dormancy. The hsfa2a knockout mutants exhibited enhanced PHS resistance while maintaining yield potential and post-harvest germination rates, offering a potential strategy to uncouple PHS resistance from agronomic penalties. Mechanistically, our data suggest that OsHsfA2a self-associates and can activate the ABA catabolic gene OsABA8ox3, thereby promoting dormancy release. Furthermore, genetic analysis using the sd6 hsfa2a double mutant supports the hypothesis that the bHLH transcription factor OsSD6 is epistatic to OsHsfA2a, acting as an upstream initiator. Biochemically, OsSD6 transcriptionally activates OsHsfA2a. Once expressed, OsHsfA2a likely amplifies the signal via a self-activation loop. However, the accumulating OsSD6 protein physically interacts with OsHsfA2a, which we propose competitively attenuates its DNA-binding capacity. These results support a multi-tiered regulatory module operating across both transcriptional and post-translational levels. Collectively, our findings provide insights into an intrinsic physiological mechanism by which this module fine-tunes ABA catabolism to govern primary seed dormancy, providing precise genetic targets for mitigating PHS.

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.

The trade-off between leaf hydraulic efficiency and safety is among the principal theories explaining plant drought adaptation, but whether rhizobium inoculation modulates this trade-off to enhance plant drought adaptation remains unclear. Here, leaf water potential (Ψ_leaf), stomatal conductance (g_s), photosynthesis (An) and leaf hydraulic conductance (K_leaf) during and after drought were measured in rhizobium-inoculated and non-inoculated Glycine max and Caragana korshinskii grown under well-watered (WW), moderate drought stress (MS) and severe drought stress (SS) conditions. Non-inoculated plants of each species exhibited a more negative Ψ_leaf, decreasing the maximum K_leaf (K_leaf-max), a more negative Ψ_leaf at 50% loss of K_leaf-max (K_leaf P₅₀), lowering the g_s and A_n, and delayed recovery from drought when grown under increasing drought severity, displaying a significant trade-off between K_leaf-max and K_leaf P₅₀. However, compared with non-inoculated plants, inoculated plants exhibited greater drought tolerance because of the improved Ψ_leaf, revealing a new trade-off relationship characterised by a greater K_leaf-max and a more negative K_leaf P₅₀, increased g_s and A_n, a more rapid recovery from drought, greater biomass accumulation and increased nitrogen and phosphorus contents. Our results suggest that rhizobium inoculation improves hydraulic safety and efficiency and recovery from drought, thus provides drought tolerance in legume species.

Studies indicate that elevated CO₂ (eCO₂) can exacerbate the damage caused by brown planthopper Nilaparvata lugens to rice plants compared to ambient CO₂ (aCO₂), though the underlying mechanism remains unclear. In this study, targeted metabonomics analysis showed that the differential secondary metabolites of rice plants under aCO₂ and eCO₂ were mainly enriched in the "flavone and flavonol biosynthesis" pathway, and the contents of six flavones (i.e., apigenin, apigetrin, cynaroside, luteolin, orientin and rhoifolin) that could stimulate N. lugens feeding were significantly increased in rice plants under eCO₂. Meanwhile, knockdown of OBP7 of N. lugens markedly reduced this feeding stimulation. In vitro fluorescence competitive binding assays verified the specific binding between OBP7 and feeding-stimulating flavones. Molecular docking and site-directed mutagenesis further identified Gly132, Gly135, His136 and Glu137 as essential residues mediating OBP7-flavone interactions. Additionally, virtual screening and functional validation identified benzoylpaeoniflorin as a competitive inhibitor of OBP7-flavones, suppressing feeding and inducing oxidative stress in N. lugens. Exogenous application of benzoylpaeoniflorin effectively mitigated the aggravating damage of N. lugens to rice plants under eCO₂. These findings elucidate how OBP7 in N. lugens senses eCO₂-induced flavones to aggravate herbivory, offering novel pest control strategies under climate change scenarios.

Plant growth and productivity are severely constrained by abiotic and biotic stresses, which disrupt essential physiological processes, particularly nutrient and ion homeostasis. In response to these challenges, plants activate sophisticated molecular networks, with transcription factors (TFs) emerging as central regulators that integrate stress signals with nutrient management. This review synthesizes current knowledge on the pivotal role of TFs in coordinating stress resilience and nutrient acquisition. It elaborates on how distinct TF families, including AP2/ERF, NAC, MYB, and bZIP, are regulated through complex signal transduction pathways involving reactive oxygen species (ROS), phytohormones, and second messengers. Upon activation, these TFs directly modulate the expression of genes encoding nutrient transporters, ion channels, and detoxification proteins, thereby maintaining cellular ion balance and facilitating nutrient uptake under stress. Notably, specific TFs such as NLP7, HY5, and STOP1 are highlighted for their direct role in regulating the homeostasis of key nutrients like nitrate, phosphate, and metals, linking nutrient signaling to adaptive responses. On the other hand, key TF families, including WRKY, MYB, bZIP, AP2/ERF, and NAC, have also been studied for their role in biotic stress tolerance. Despite these advances, the identification of TFs that specifically govern nutrient transport under combined stresses remains limited. We conclude that advanced functional genomics, machine learning, and genetic engineering to manipulate these master regulatory networks present a transformative strategy for developing next-generation crops with enhanced nutrient use efficiency and climate resilience, which is critical for achieving global food security.

N-myristoylation is a common yet poorly understood protein lipid modification in all eukaryotes, including plants. It involves the covalent attachment of myristic acid to the N-terminal glycine of target proteins, catalyzed by N-myristoyltransferase. This modification can alter the structure and membrane anchoring of target proteins, thereby playing a significant role in regulating protein fate, including subcellular compartmentalization and stability. Currently, increasing evidence has highlighted the vital role of N-myristoylation in regulating plant immunity, abiotic stress responses, growth, and development, underscoring its biological significance for plant environmental adaptation and survival. Despite its importance, the fundamental mechanisms of N-myristoylation and its specific regulatory effects on plant protein function and fate remain incompletely characterized. In this review, we first summarize the core biochemical process of protein N-myristoylation and the functional features of its catalytic enzyme, N-myristoyltransferase. We then elaborate on the molecular basis by which this modification modulates protein fate, before providing a comprehensive overview of its diverse biological functions in the aforementioned plant physiological processes. Additionally, we critically evaluate major technical approaches for detecting N-myristoylation, clarifying their respective advantages and inherent limitations. Finally, we propose promising future directions, aiming to provide a theoretical foundation for subsequent investigations in this rapidly developing field.

Drought stress severely impacts plant growth and productivity; however, the molecular mechanisms underlying stress adaptation in non-model crops remain incompletely understood. In this study, we discovered that the SnRK2 kinase CaSnRK2.4 and the bZIP transcription factor CabZIP032 positively regulate drought tolerance through ABA and sucrose signalling pathways. Yeast two-hybrid and in planta assays confirmed direct interaction between CaSnRK2.4 and CabZIP032, with CaSnRK2.4 phosphorylating CabZIP032 at serine 251 (Ser251). Phosphorylation-defective CabZIP032^S251A mutants exhibited protein stability and compromised drought tolerance, whereas phosphomimetic CabZIP032^S251D mutants showed enhanced stress resilience. Functional analyses revealed that CabZIP032 binds to the promoters of CaABI5, an ABA-responsive gene, and CaSPS1, a sucrose biosynthesis gene, activating their transcription via specific recognition of ACGT and G-box cis-elements, respectively. Silencing of CaABI5 or CaSPS1 results in increased drought sensitivity and reduced ABA and soluble sugar levels. Notably, exogenous applications of ABA or sucrose rescued drought tolerance in CabZIP032-silenced plants, while phosphorylation at Ser251 further potentiated CabZIP032 transcriptional activity. Collectively, these findings establish a CaSnRK2.4-CabZIP032 signalling module that orchestrates drought adaptation by stabilising CabZIP032 through phosphorylation, thereby promoting ABA signalling and sucrose accumulation. This study reveals a conserved regulatory mechanism in pepper and provides potential molecular targets for engineering drought-resilient crops.