Annual review of plant biology最新文献

Nicotinamide adenine dinucleotide (NAD) is an essential coenzyme in cellular metabolism with a long-established role in energy production, biosynthesis, and oxidative stress responses. Recent research demonstrates that NAD hydrolysis is a key step in immune signaling, beyond its primary metabolic functions. Here, we review how NAD and NAD-derived small molecules influence defense-related processes including reactive oxygen species production, calcium dynamics, and immune activation. We introduce diverse NAD-modifying enzymes in plants and discuss how they regulate immunity, with a special emphasis on Toll/interleukin 1 receptor (TIR) domain proteins, which hydrolyze NAD+ to produce immune-activating molecules. We also discuss how pathogens use NAD-modifying enzymes as virulence factors to manipulate host defenses, highlighting NAD metabolism as a newly emerged, critical battleground in the plant-pathogen arms race. Recent developments in this aspect of pathogenesis offer new opportunities to enhance disease resistance.

Plants generate long-range signals via complex mechanisms that integrate electrical, calcium, and chemical signals. While animals employ synaptic/neural connections for cell-cell and organ-organ signal transduction, plants depend on specialized structures, such as plasmodesmata and vascular bundles. This review examines recent advances in elucidating these plant-specific long-range signal mechanisms, emphasizing the initiation, propagation, and integration of diverse signals throughout the plant body. We highlight how the combination of traditional electrical potential measurements and modern bioimaging techniques, particularly genetically encoded fluorescent indicators, has improved our understanding of long-range signals in various plant species, including Arabidopsis thaliana, Mimosa pudica, and Dionaea muscipula. These technological advancements have enabled the development of integrated models that encompass biological components (e.g., ion channel activities), chemical mechanisms (e.g., compound diffusion), and physical processes (e.g., hydraulic signals). This integration offers new insights into how plants coordinate systemic responses across spatially distant organs.

γ-Aminobutyric acid (GABA), a nonproteinogenic amino acid first identified in biological systems over 70 years ago, has long been recognized as a metabolic intermediate. More recently, GABA has also been acknowledged as a signaling molecule that couples physiological responses to metabolic status. This review presents a conceptual framework for how metabolism sets GABA concentration and localization, which then modulate ion transport and membrane potential dynamics to influence plant growth, development, and adaptation to stress. We explore the emerging network of GABA's interactions with other signaling pathways, highlighting its involvement in environmental sensing and internal regulatory mechanisms via hormones and reactive oxygen species. These interactions influence key physiological processes including stomatal regulation, pathogen and herbivore defense, root growth, and even the modulation of flavor. Collectively, these findings position GABA as a metabolic signal integrator of plant physiological status and responses, with broad implications for enhancing crop stress resilience and food quality.

Plants and microbes exchange macromolecules such as RNA and proteins. How this exchange is accomplished is poorly understood, but extracellular vesicles (EVs) have been proposed as likely vehicles. Here, we review recent work on the biogenesis and functions of plant EVs and the current evidence in support of and against their role in cross-kingdom RNA interference. Plant EVs, like EVs from other kingdoms of life, are released in part by the fusion of multivesicular bodies with the plasma membrane, a complex and conserved mechanism involving lipid-modifying proteins, the exocyst complex, and Rab GTPases. Though some plant EV subpopulations are involved in immunity, it appears unlikely that plant EVs contribute to cross-kingdom RNA interference. Recent work has shown that plants secrete extravesicular RNA, including small RNAs and long noncoding RNAs, into the leaf apoplast and onto leaf surfaces, while very little RNA is found inside of EVs. We propose that these free extracellular RNAs play a central role in maintaining a healthy leaf microbiome.

Pyrenoids are eukaryotic CO₂-fixing organelles that are evolutionarily diverse, globally abundant, and critical to global carbon cycling. Despite being described over 200 years ago, the vast majority of our molecular understanding of pyrenoids has emerged only in the past decade. Here, we review the recent advances in characterizing pyrenoid structure, function, and evolutionary variation across lineages containing primary, secondary, and tertiary plastids of both red and green origins. We outline experimental frameworks that can be used to answer key questions about these enigmatic organelles. We discuss the utility of pyrenoids as model biomolecular condensates for investigating fundamental properties of liquid-liquid phase separation. Finally, we summarize how understanding convergently evolved pyrenoids across diverse lineages may be used to advance efforts to engineer functional pyrenoids into crop plants to enhance CO₂ fixation for yield improvements and carbon dioxide removal.

This article traces more than four decades of Eva Kondorosi's personal life and scientific journey in symbiotic nitrogen fixation, from early insights into nitrogenase structure to the molecular mechanisms governing root nodule development and symbiotic cell differentiation in the Medicago-Sinorhizobium meliloti symbiosis. Effective symbiosis depends on precise molecular communication between the partners, beginning in the soil and continuing through a highly coordinated, progressive differentiation program. A defining feature of symbiotic cell development is endoreduplication in both host plant cells and their Rhizobium partners. Host-induced bacterial endoreduplication results in the formation of large, polyploid, noncultivable nitrogen-fixing bacteroids. This terminal differentiation is orchestrated by plant-derived effector peptides, notably nodule-specific cysteine-rich (NCR) and nodulin glycine-rich (nodGRP) peptides, which act sequentially to reprogram bacterial physiology. Together, these findings establish symbiotic nitrogen fixation as a model for cross-kingdom cellular differentiation and highlight NCR and nodGRP peptides as a vast, largely unexplored resource with promising applications in agriculture and medicine.

The transition from one pollination syndrome to another should be difficult as it requires coordinated changes of multiple component traits, with each involving multiple genes, yet these transitions occur frequently in nature. Here, we explore the genetic and genomic properties that facilitate such rapid pollination syndrome switches. We begin this review by recognizing the important role of relaxed pollinator specificity and delayed selfing in providing adaptive continuity during pollinator shifts. We then compare theoretical predictions with empirical studies on the genetic architecture and molecular basis underlying pollination syndrome divergence. We find that dominance, pleiotropy, tight genetic linkage, and standing genetic variation are important contributors and highlight the novel insights provided by detailed molecular characterizations. We conclude by suggesting where future efforts can help us bridge the genetic basis of individual trait divergence, the fitness effect of each variant, and the genome-wide recombination landscape into a coherent, predictive framework.

Biomolecular condensates have emerged as versatile regulators of plant cellular processes, offering a dynamic and reversible mechanism to coordinate development, stress response, and spatial organization. Through phase separation, these condensates spatially and temporally modulate biochemical reactions, sequester or activate specific proteins and RNAs, and reshape cellular architecture. This review presents a comprehensive and multidimensional framework for understanding biomolecular condensates in plant biology, from their biophysical properties and ensemble dynamics to their roles across diverse cellular compartments, including plasma membranes, cytoskeleton, intracellular compartments, and chromatin. We highlight their functions in growth, environmental sensing, and defense and discuss current challenges in studying their composition, material properties, and context-dependent behaviors. Understanding plant condensates not only deepens our knowledge of plant cell organization and adaptability but also opens new avenues for biotechnological innovation in agriculture.

Plant hormones are essential small molecules that regulate plant growth, development, and systemic responses to environmental stimuli. These processes are mediated by complex signaling networks involving structurally diverse receptors, regulatory proteins, and dynamic protein-protein interactions. Advances in structural and functional biology over the past two decades have revealed how hormone receptors recognize their ligands and how they mediate responses from perception to signaling through transduction pathways and feedback regulation. In this review, we summarize the current knowledge of plant hormone receptors with experimentally determined structures and highlight their central roles in shaping plant biology. Finally, we discuss outstanding questions in the field and how emerging computational tools may help address these gaps.

Chloroplasts, the photosynthetic organelles of plants and algae, rely on the import of thousands of nuclear-encoded proteins to sustain their diverse physiological roles. This process is mediated by the coordinated action of the translocon at the outer chloroplast membrane (TOC), the translocon at the inner chloroplast membrane (TIC), and an ATP-driven import motor. However, research on these key machineries has long been intensely debated in the field. Recent advances in structural characterization have now resolved long-standing controversies regarding the composition and architecture of these complexes. This review summarizes the most recent structural, functional, and evolutionary insights into the chloroplast protein import apparatus, emphasizing the transformative role of high-resolution structural biology in redefining long-held paradigms.