Wu Wenqi, Du Kang, Kang Xiangyang, Wei Hairong
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, PR China.
National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China.
Hortic Res. 2021 Jun 1;8(1):118. doi: 10.1038/s41438-021-00558-3.
Leaves provide energy for plants, and consequently for animals, through photosynthesis. Despite their important functions, plant leaf developmental processes and their underlying mechanisms have not been well characterized. Here, we provide a holistic description of leaf developmental processes that is centered on cytokinins and their signaling functions. Cytokinins maintain the growth potential (pluripotency) of shoot apical meristems, which provide stem cells for the generation of leaf primordia during the initial stage of leaf formation; cytokinins and auxins, as well as their interaction, determine the phyllotaxis pattern. The activities of cytokinins in various regions of the leaf, especially at the margins, collectively determine the final leaf morphology (e.g., simple or compound). The area of a leaf is generally determined by the number and size of the cells in the leaf. Cytokinins promote cell division and increase cell expansion during the proliferation and expansion stages of leaf cell development, respectively. During leaf senescence, cytokinins reduce sugar accumulation, increase chlorophyll synthesis, and prolong the leaf photosynthetic period. We also briefly describe the roles of other hormones, including auxin and ethylene, during the whole leaf developmental process. In this study, we review the regulatory roles of cytokinins in various leaf developmental stages, with a focus on cytokinin metabolism and signal transduction processes, in order to shed light on the molecular mechanisms underlying leaf development.
叶片通过光合作用为植物提供能量，进而为动物提供能量。尽管叶片具有重要功能，但其发育过程及其潜在机制尚未得到充分表征。在此，我们以细胞分裂素及其信号功能为核心，对叶片发育过程进行全面描述。细胞分裂素维持茎尖分生组织的生长潜能（多能性），在叶片形成的初始阶段，茎尖分生组织为叶原基的产生提供干细胞；细胞分裂素和生长素及其相互作用决定叶序模式。细胞分裂素在叶片各个区域，尤其是边缘区域的活性，共同决定了叶片的最终形态（例如，单叶或复叶）。叶片面积通常由叶中细胞的数量和大小决定。在叶片细胞发育的增殖和扩展阶段，细胞分裂素分别促进细胞分裂并增加细胞扩展。在叶片衰老过程中，细胞分裂素减少糖分积累，增加叶绿素合成，并延长叶片光合作用期。我们还简要描述了包括生长素和乙烯在内的其他激素在整个叶片发育过程中的作用。在本研究中，我们综述了细胞分裂素在叶片不同发育阶段的调控作用，重点关注细胞分裂素代谢和信号转导过程，以阐明叶片发育的分子机制。
