Annual review of plant biology最新文献

Plant cells possess functionally specialized RNA polymerases (RNAPs) in both the nucleus and the chloroplast. In addition to the conserved RNA polymerase I (Pol I), Pol II, and Pol III, the nuclear genome of land plant cells encodes two unique multiple-subunit DNA-dependent RNAPs-Pol IV and Pol V-which produce noncoding RNAs for nuclear gene silencing. The plastid genome of all plant cells also encodes a unique multiple-subunit DNA-dependent RNAP-the plastid-encoded RNAP (PEP). Phylogenetic analyses indicate that these plant-specific RNAPs have clear evolutionary origins: Pol IV and Pol V diverged from Pol II, while PEP originated from cyanobacterial RNAP. Over billions of years, these plant-specific RNAPs underwent functional specialization through losing key residues, motifs, and domains essential to their ancestors' function and gaining new motifs, domains, and subunits tailored to their distinct roles. This review explores the evolutionary loss-and-gain strategy that shaped the three plant-specific RNAPs.

Cryo-electron tomography (cryo-ET) is a transformative technique in cell biology that enables three-dimensional visualization of cellular structures in near-native states and at nanometer and even subnanometer resolution. Unlike traditional imaging methods, cryo-ET preserves the ultrastructure of cells without chemical fixation or staining, allowing researchers to observe macromolecular complexes in situ. Cryo-focused ion beam milling has overcome sample thickness limitations, enabling high-resolution imaging of complex and large specimens. When combined with correlative light microscopy and subtomogram averaging, cryo-ET can localize and resolve macromolecular assemblies within the cell. We discuss how cryo-ET has provided unprecedented insights into cellular architecture by bridging the gap between molecular and cellular scales and highlight examples in photosynthetic organisms. We also discuss new efforts to increase automation, throughput, and validation that make cryo-ET accessible to a larger community of scientists, including plant biologists.

RNA interference (RNAi) has emerged as a promising approach to sustainable crop protection. Extensive proof-of-concept studies have led to the approval of the first sprayable plant protection products in the United States and China, with Europe currently evaluating them. Although gene silencing mechanisms are among the most extensively studied processes in molecular biology, with two Nobel Prizes recognizing their discovery, the optimization of delivery systems and field performance remains an area currently undergoing extensive development. The uptake, stability, and efficacy of double-stranded RNA (dsRNA) are influenced by species-specific and environmental factors, introducing variability that must be understood in order to select robust targets, design effective dsRNA, and assess risk. Although these knowledge gaps remain, they are increasingly addressed through systematic experimental and technological advances. This review summarizes the current knowledge on RNAi mechanisms in plants, fungi, and insects, emphasizing the differences in dsRNA uptake and processing between species. We highlight advances in formulations and delivery technologies, discuss how regulatory and ecological questions are being systematically investigated, and present examples of approved products that demonstrate the approach's feasibility and safety. Finally, we outline how remaining uncertainties can be addressed through targeted research and risk-mitigation strategies and how RNAi technologies can be incorporated into comprehensive pest and disease management systems.

Inositol phosphates and pyrophosphates are small, water-soluble molecules involved in a range of physiological processes across eukaryotic organisms, including plants. Over the past two decades, significant advancements in inositol (pyro)phosphate detection and chemical synthesis, coupled with the characterization of plant mutants and the structural analysis of receptors and associated proteins, have greatly enhanced our understanding of their production, degradation, and perception in plants. This growing knowledge base demonstrates that inositol (pyro)phosphates are crucial for regulating key processes, such as phosphorus homeostasis, hormone signaling, and plant-microbe interactions. We provide a global perspective on these processes, highlighting recent discoveries, new possibilities, and unresolved questions.

Phenotypic plasticity (PP) is a fundamental property of plants, enabling a single genotype to produce different phenotypes in response to environmental variation. This ability is crucial for survival and reproduction in heterogeneous habitats, allowing plants to optimize their physiology, development, and growth under changing conditions. Widespread natural genetic variation for plasticity enables selection to shape environmental responses. This review synthesizes the current knowledge on the genetic and molecular mechanisms underlying PP in plants, highlighting its importance for crop breeding and for enhancing resilience to climate change. We discuss experimental approaches to quantify plasticity and identify its genetic basis and consider factors that may constrain the evolution of plasticity. We also explore how advances in the analysis of multisite field trials and genomic prediction have propelled the study of PP in agriculture. Ultimately, a deeper understanding and targeted use of PP hold promise for developing crop varieties that can maintain stable yields in increasingly variable environments.

RAF-like protein kinases constitute a major subclass of mitogen-activated protein kinase kinase kinases (MAPKKKs) in plants and function as critical regulators of stress and hormone signaling pathways. Unlike their animal counterparts, plant RAF kinases show extensive expansion and diversification, with distinct subgroups (B and C) exhibiting both conserved and specialized functions. Recent studies have unveiled their pivotal roles in sensing environmental stresses, such as hyperosmotic stress and elevated CO₂, as well as in mediating hormonal responses, including those to abscisic acid (ABA), ethylene, and auxin. RAFs also participate in guard cell signaling, immune responses, and developmental processes, integrating diverse external and internal cues. This review summarizes the current knowledge of plant RAF kinases, emphasizing their functional diversity, mechanisms of activation, and physiological relevance in plant adaptation.

Gravitropism allows plants to reorient their growth along the gravity vector by sensing and responding to changes in orientation. This review summarizes recent advances in elucidating the molecular mechanisms underlying gravity sensing and signal transduction, with a focus on flowering plants. Central to this process are starch-filled amyloplasts that sediment within statocytes and activate downstream signaling pathways. Recent discoveries include the identification of LAZY1-LIKE family proteins, which translocate from amyloplasts to the plasma membrane in response to gravi-stimulation and recruit regulators such as RLDs and D6PKs to control polar auxin transport. We also discuss the emerging concept of antigravitropic offset, which modulates lateral organ angles, and its potential mechanistic divergence from classical gravitropism. Collectively, these findings reveal an integrated system to regulate organ orientation and plant architecture.

All organisms fuel and build themselves through their energy metabolism. While classic biochemistry conceptualizes the fluxes of energy and matter, our understanding of how energy metabolism works in vivo contains major gaps. One reason is that energy metabolism spans multiple scales, from enzymes to organs, and shifts dynamically at environmental and developmental transitions, resulting in a degree of complexity that is presently impossible to capture. Genetically encoded fluorescent biosensors have started to bridge several critical gaps by enabling live monitoring of metabolites across scales. Recently, several paradigms of energy metabolism have started to shift, driven by the expansion of biosensing tools. This review explores advancements in our understanding of plant energy metabolism driven by fluorescent protein biosensing, highlights emerging concepts and open questions, and discusses how available tools, and much-needed future innovations, can unlock the potential of biosensing toward understanding in vivo plant energy metabolism and its effective modification.

Membrane lipid composition underpins the structural and functional identity of all plant membranes. This review examines membrane lipid metabolism and trafficking, with an emphasis on how lipid diversity and interorganelle movement support plant cell function. We explore the biophysical and biochemical specialization of subcellular membranes, with discussion of the endoplasmic reticulum, plasma membrane, apoplastic vesicles and barriers, tonoplast, peroxisomes, mitochondria, plastids, and thylakoids. We review both vesicular and nonvesicular lipid transport pathways, including membrane contact sites. Particular attention is given to glycerolipids, including phospholipids and galactolipids, sphingolipids, sterols, and, to a lesser extent, fatty acid exchange. By focusing on mechanisms of lipid transfer and remodeling, this review synthesizes our understanding of subcellular membrane lipid composition in the context of dynamic cellular processes including cell plate expansion, environmental stress responses, and photosynthetic membrane assembly.

The advent of spatial and quantitative biology has led to immense advances in understanding the complex inner workings of plants, down to the molecular scale. Functional imaging of live plants, which enables the spatial and quantitative mapping of biochemical cues, physicochemical properties of cellular structures, and the dynamics of physical and chemical signals with unprecedented resolution, has become a key technology for advancing the mechanistic understanding of plant cell biology. In this review, we highlight progress in live functional imaging in plants through the use and development of chemical fluorescent probes, which enable plant functional imaging without requiring genetic manipulation of the study object. We explain how probes sense, target, and report on functional features within the plant cell; discuss their limitations, including toxicity; and provide case studies to exemplify how these tools can complement biological studies to unravel the complex machinery that makes plants work. We conclude by outlining the expected future development of this field and identifying key challenges that lie ahead.