Molecular Plant最新文献

Salicylic acid (SA) is a pivotal plant hormone that modulates immune responses in a pathogen-lifestyle-dependent manner, typically amplifying defenses against biotrophic and hemibiotrophic pathogens. Foundational research in Arabidopsis established a paradigm for SA biology, elucidating the isochorismate synthase (ICS) pathway for SA biosynthesis, the mechanisms regulating SA levels, the role of NPR proteins as SA receptors, and the downstream signaling pathways that confer immunity. However, recent studies in other species such as Nicotiana benthamiana and rice have revealed a complete phenylalanine-derived SA biosynthesis pathway that is widespread among seed plants. In contrast, the ICS pathway appears to be a recent evolutionary innovation specific to the Brassicales order. This review synthesizes the established knowledge of SA biology in Arabidopsis, discusses insights into the alternative pathways and evolution of SA biosynthesis and signaling across diverse plants, and outlines key outstanding questions for future research.

Soil salinity and drought are major environmental constraints that significantly affect crop growth and yield. Although meaningful progress has been made in deciphering plant responses to salt and water deficit, the primary sensing mechanisms plants use to perceive these stresses remain unknown. Both salinity and drought induce hyperosmotic stress in plant cells (Van Zelm et al., 2020). Yet, what exactly allows plants to perceive drought or salt? Do they sense mechanical stress in their cell wall, a loss of cell volume, the tension in the plasma membrane, or do they "simply" detect Na⁺ and/or Cl^- in the case of salinity? A bona fide abiotic stress sensor has been defined as the primary sensor that directly senses an environmental condition and via cellular signaling leads to a physiological response (Lamers et al., 2020). Here, we highlight some of the recent significant advances in the identification of such a sensory mechanism for water deficit and salt. By drawing parallels to animals and cyanobacteria, we offer a fresh perspective and propose new hypotheses on plant drought and salt-sensing mechanisms (Figure 1fig1). Finally, we challenge assumptions in the field and highlight promising research gaps to make advances in the identification of the drought and salt sensors in plants.

Strigolactones (SLs) are carotenoid-derived phytohormones that regulate plant development and mediate rhizosphere interactions. Synthesized from β-carotene through a multistep enzymatic pathway, SLs modulate key physiological processes, including shoot branching, leaf development, flowering, and root growth. In addition to performing endogenous hormonal roles, SLs are exuded into the soil, where they serve as ecological signals. Exuded SLs facilitate symbiotic relationships with arbuscular mycorrhizal fungi to enable nutrient exchange and are also exploited by parasitic weeds to locate host plants. Although the core SL biosynthesis and signaling pathways have been extensively characterized, research continues to uncover new layers of complexity in their regulation and function. Here, we present a comprehensive overview of SLs, summarizing the past major achievements and recent advances in their biosynthesis, transport, perception, and signal transduction, together with their multifaceted functions. We discuss current challenges in SL research and highlight important questions for future investigations. Addressing these issues can further enhance our understanding of the SL pathway and promote its application in agriculture.

Rice serves as a cornerstone of global food security, feeding over half of the world's population, yet it faces increasingly severe challenges from population growth, climate change, biotic stresses, and resource limitations. In the past 60 years, remarkable achievements have been made in fundamental research and rice breeding, supporting the quadrupled global rice production. However, the current growth rate of rice yield has stagnated at ∼0.5% annually, insufficient to meet projected food demand for 2050 or beyond. In this Perspective article, we briefly summarizes the developmental trajectories of rice fundamental research and breeding, and retrace the shift in rice breeding goals and research stages, encompassing the milestone events in Green Revolution, hybrid rice breeding, and molecular design breeding. We then emphasize the persistent challenges in limited genetic diversity, trade-offs between yield and resistance, and nutrient utilization and articulate the breeding objectives of "Two Increases and Two Decreases" for the next decade in enhancing yield and quality while reducing fertilizer and pesticide inputs and yield loss in response to disasters. To address these challenges, we overview and prospect current and future cutting-edge technologies, research methodologies, and breeding approaches, focusing on expanding genetic diversity, deciphering the molecular basis of key traits, and improving breeding efficiency. These efforts aim to facilitate the realization of the "Rice 2035" breeding goals, thereby ensuring global food security.

Heritable epimutations can lead to transmittable phenotypic variation. However, the contribution of epigenetic variations to phenotypic diversity in plant evolution and crop domestication remains elusive. Here, we constructed a comprehensive DNA methylation atlas of 1,102 soybean accessions including wild soybeans, landraces and improved cultivars. Integrated analysis of methylome, variome and transcriptome unveiled that de novo epimutations contributed to an increase in epigenetic diversity following the domestication bottleneck and played a role in modulating gene expression during soybean evolution. Epigenome-wide association study and targeted DNA methylation editing validated an epiallele governing expression of GmFT5a, which contributed to replicated evolution of earlier flowering during high-latitude adaptation of both wild and cultivated soybeans. Notably, the integration of both genetic and epigenetic variants substantially increased the proportion of phenotypic variance explained, capturing a larger fraction of the heritability for these agronomic traits. This study emphasizes the considerable potential of epialleles for crop improvement and may pave the way for epigenetics-driven breeding.

Stem cell niches in both plants and animals are frequently located in low-oxygen microenvironments that support their function. In plants, these hypoxic niches promote local stabilization of several transcriptional regulators that control a range of developmental processes including shoot apical meristem activity, vernalization, lateral root development, and leaf growth and morphogenesis. Despite their importance, however, it remained unclear how these hypoxic niches are maintained. Here, we employed a combination of experimental and modeling approaches to identify the key features required to establish and sustain the hypoxic niche enclosing the shoot apical meristem. Using respiration inhibitors, manipulation of resource availability, and mitochondria mutant lines, we found that respiratory oxygen consumption is required to establish the hypoxic niche. Oxygen microprofiling and imaging of hypoxia signaling in cuticle biosynthesis mutants, as well as following targeted cuticle degradation, revealed that a cuticle-like barrier defines the steepness of the oxygen gradient and ensures that even the outermost layer remains hypoxic. Moreover, high tissue compactness in the shoot apex region was visualized using X-ray micro-computed tomography and shown to stabilize the hypoxic microenvironment by limiting internal oxygen diffusion. Finally, sensitivity tests on a novel reaction-diffusion model closely recapitulated oxygen gradients across the shoot apical meristem and revealed distinct roles of each feature and their combined effect on oxygen distribution. Together, these findings explain how the SAM sustains hypoxia and point to a potential universal strategy used by stem cell niches to maintain low oxygen levels.