生命科学最新文献

Expansins are fundamental agents of plant growth and adaptation, enabling cell walls to expand and remodel through unique non-enzymatic mechanisms. This review elucidates the structural biology, evolutionary history, and physiological versatility of these essential proteins. Characterised by a conserved two-domain architecture, a GH45-like domain (D1) and a CBM63-like domain (D2), expansins facilitate "acid growth" by physically disrupting hydrogen bonds at the cellulose-matrix interface without polymer hydrolysis. This article extends the indispensable roles of expansins throughout the plant life cycle, from sculpting root and shoot architecture to regulating reproduction in pollen tube growth, fruit softening, and seed germination. Furthermore, the review emphasises their function as critical modulators of plant resilience, illustrating how expansin-mediated cell wall remodelling drives adaptation to abiotic stresses as well as to biotic challenges.

Soil salinisation poses a formidable threat to global agricultural productivity. It induces osmotic stress, ion toxicity and systemic oxidative damage in crops. Breeding salt-tolerant varieties is time-consuming. This creates an urgent need for rapid and sustainable agronomic interventions. Algae and their bioactive extracts, such as polysaccharides, phytohormones and polyols, act as potent biostimulants and biofertilizers. They effectively function as exogenous elicitors. This review synthesises the multidimensional interactions between algae and plant defence systems under salt stress. We evaluate how compounds derived from algae orchestrate plant tolerance to salt. They bypass or synergise with endogenous signalling pathways to reprogramme transcriptional networks. We delineate the mechanisms underpinning ionic homoeostasis mediated by algae. These include SOS pathway modulation, osmotic adjustment, reactive oxygen species scavenging, and hormonal crosstalk through pathways dependent on or independent of ABA. Furthermore, we critically compare algae extracts with other biostimulant classes and dissect their crop-specific efficacies under multifactorial combined stress scenarios. The focus then shifts from molecular paradigms to agricultural applications. Integrating algae into soil microbiomes and broader soil remediation strategies significantly enhances rhizosphere health. Translating these advances from controlled laboratory conditions to efficacy at the field scale remains a prominent bottleneck. We highlight current knowledge gaps and propose future trajectories, including multiple omics integration, synthetic biology, precision agriculture integration, and nanoscale delivery systems. These approaches will help fully harness the potential of the algae and plant holobiont for agriculture adapted to climate change.

Many molecular mechanism-related details for maize to respond to and tolerate combined high air temperature and natural soil drought (HAT-NSD) stress especially via whole genome-wide DNA methylation (WGDM) are not-yet known. This study focused on addressing molecular mechanisms of maize response to HAT-NSD by multi-level approaches. The main findings included 4315 differentially methylated genes (DMG); DNA motif sequences prone to differential methylation (DM); heterozygous and homozygous variations in SNPs and InDels; differential alternative splicing (AS) events of mRNAs; high- and low-density DM regions on chromosomes; positive and negative correlations between WGDM and whole-genome gene expression, depending on C (CG, CHG and CHH) contexts in gene regions; 4186 differentially expressed genes (DEG); 1607 differentially expressed proteins (DEP); the limited impacts of whole-genome DM on protein abundance via DMG-DEG-DEP type genes; reprogramming of whole-genome gene expression and flowering by whole-genome DM under HAT-NSD, involving differential AS events and feedback from the follow-up effects of the DM; and functions of ZmSOS3-3 and ZmSOS5-2 genes in both HAT-NSD tolerance and flowering. Models of DM-driven reprogramming-feedback gene expression and flowering/tasseling of maize under HAT-NSD were proposed. The findings provide new insights into mechanisms for maize responses to HAT-NSD through WGDM.

Conventional wisdom views winter as ecologically dormant, overlooking a critical phase in the annual nitrogen (N) cycle. This review establishes the 'winter N pump' as a key conceptual framework, reframing the cold season as an active control point for ecosystem N budgets. Beneath the snowpack, cold-adapted soil microbes drive continuous N transformations, accumulating a substantial hidden N reservoir. Simultaneously, woody plants take up and store N during winter, while herbaceous plants do not resume N acquisition until spring. Spring snowmelt releases this reservoir in a synchronised pulse, and together with the N stored in woody plants, it fuels initial spring growth. Thus, the pump acts as a critical 'pre-positioning' mechanism that directly links winter biogeochemical processes to growing-season productivity. Climate change, through winter warming, earlier spring snowmelt, and intensified freeze-thaw cycles, is disrupting this coupling, thereby decoupling the spring N pulse from plant N demand, potentially increasing N losses via leaching and denitrification, particularly in vulnerable ecosystems. Integrating winter N dynamics into ecological models and empirical research is therefore essential to accurately predict future ecosystem productivity, carbon sequestration and biogeochemical feedback. Explicit incorporation of the 'winter N pump' concept is crucial for developing strategies to maintain nutrient cycling and ecosystem resilience under global climate change.

Although plants are exposed to many environmental stressors (heat, drought, salinity, and pathogen), they survive by rapidly reprogramming their gene expression. Recent findings show that many regulatory mechanisms are maintained within liquid-liquid phase separation (LLPS) formed biomolecular condensates, instead of maintaining these mechanisms within membrane-bound organelles. LLPS has been shown to exist in plant cells; however, the integration of LLPS with functional stress adaptations and gene regulations is still unclear from the studies that have been published thus far. In this review, we discuss recent research that demonstrates how these biomolecular condensates act as dynamic regulatory centers by linking environmental stress perception to transcriptional and post-transcriptional regulation of genes in plants. We describe the biophysical principles that govern the occurrence of LLPS in a plant cellular environment and provide an overview of how both abiotic (e.g., drought, heat) and biotic (i.e., pathogens) stressors initiate the LLPS and remodel nuclear and cytosolic condensate structures. The focus of this work will be on the effects of stress-induced changes (both qualitatively and quantitatively) in the condensate composition and material properties on transcription factor activity (either as an activator or repressor) and the organization of chromatin, RNA stability, and selective translation. We will also discuss post-translational modifications (PTMs) that modulate condensate dynamics and allow for reversibility. Collectively, these findings suggest that LLPS likely contributes significantly to gene regulation and stress adaptation in plants, although the degree of mechanistic validation varies among different condensate systems.

Saline-alkali stress is a major abiotic factor that compromises plant growth, crop yield, and quality. Cytokinin plays an essential role in plant responses to saline-alkali stress; however, the underlying molecular mechanisms remain unclear in apple (Malus domestica). In this study, CYTOKININ OXIDASE/DEHYDROGENASE7 (MdCKX7) was identified as a positive regulator of saline-alkali tolerance in apple, encoding a functional CKX enzyme that mediates cytokinin degradation. Consistently, applying exogenous lovastatin, an inhibitor of cytokinin biosynthesis, alleviated the saline-alkali-sensitive phenotype in MdCKX7-silenced plants by promoting stomatal closure through cytokinin degradation. Molecular genetic assays revealed that apple transcription factor MdSPL1 is involved in the response to saline-alkali stress by directly activating the expression of MdCKX7. Overexpression of MdSPL1 enhanced saline-alkali tolerance by modulating photosynthetic efficiency and stomatal aperture, whereas its silencing resulted in increased sensitivity. Furthermore, overexpression of MdCKX7 in the MdSPL1-RNAi background rescued the saline-alkali-sensitive phenotype. Further analysis revealed that MdNF-YB4, a positive regulator of saline-alkali tolerance, interacts with MdSPL1 to facilitate its transcriptional activation of MdCKX7. Collectively, our study reveals the MdSPL1-MdNF-YB4-MdCKX7 regulatory module that orchestrates cytokinin-mediated saline-alkali tolerance in apple, providing valuable molecular tools for the breeding of saline-alkali-tolerance apple varieties.

The interaction between soil texture and water shapes root adaptation, though the underlying mechanisms remain unclear. This study investigated the physiological and transcriptional mechanisms by which soil texture regulates tomato root responses to water stress. We conducted using three soil textures-silty clay (SC), loam (L), and sandy loam (SL) under two irrigation regimes: well-watered (WW, 70%-90% field capacity, FC) and water deficit (WD, 40%-60% FC). Among SC, L, and SL, available water content (AWC) and penetration resistance (PR) gradually increased, while air-filled porosity (AFP) decreased and water stress further reduced AWC and increase both PR and AFP. Weighted gene co-expression network analysis (WGCNA) of root physiological, transcriptomics, and soil physical properties revealed that soil texture modulates the adaptive strategies of tomato roots to water stress. Under water stress, roots in SC upregulate respiratory enzymes to enhance root respiratory activity, and also upregulate lignin biosynthesis-related genes, leading to earlier lignin accumulation. In SL, roots upregulated genes involved in lignin synthesis and cell wall expansion, accelerating lignin deposition and cell wall thickening, while respiratory activity decreased. In L, roots upregulated nitrate transporter and aquaporin genes to coordinate nitrogen and water uptake, while maintaining relatively high respiratory activity. Partial least squares structural equation modelling (PLS-SEM) was employed to construct pathways elucidating the relationships among key genes, soil physical properties, and root physiological indicators. The study unravelled the cooperative mechanism by which soil texture and water stress modulate root growth through soil physical properties, providing a scientific basis for managing different soil textures under water-limiting conditions.

Polyploidy shapes plant physiology and anatomy, yet the extent to which different ploidy levels influence drought responses remains unclear. Here, we investigated how ploidy affects cell-level coordination and functional traits associated with water transport and retention. We used glasshouse-grown plants of the carnation Dianthus broteri, a species complex composed of naturally distinct populations differing in cytotype: diploid (2×), low-polyploid (4×), and high-polyploid (6× and 12×). Leaf anatomical traits scaled with ploidy: higher-ploidy cytotypes exhibited larger stomata and pavement cells, with coordinated reductions in stomatal and vein densities. However, the 12× cytotype deviated from this trend and displayed higher g_min and thinner epicuticular wax. Stem xylem anatomical traits and hydraulic vulnerability were largely conserved, except for thicker intervessel pit membranes in 6× and 12× individuals, which correlated with delayed embolism spread (P₂₅). Plant structure-function trait combinations indicate that cytotypes differ in water-use syndromes rather than aligning along a single dimension of drought response. Under drought conditions, lower ploidies maintained functional canopies through reduced water loss, whereas 12× showed a less conservative water-use strategy and seasonal canopy loss. Altogether, we provide new insights into how polyploidy can influence drought adaptation and survival strategies via anatomical and functional trait shifts.