Sakakibara Hitoshi
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama, Japan.
J Exp Bot. 2025 May 10;76(7):1941-1949. doi: 10.1093/jxb/erae348.
Cytokinins, a class of phytohormones, play crucial roles in regulating plant growth and stress responses through finely tuned feedback loops involving metabolic and signaling cascades. Over the past 25 years, studies have identified key genes involved in cytokinin biosynthesis and inactivation pathways. Nevertheless, several gaps remain in our understanding, particularly regarding the movement of intermediate metabolites between subcellular compartments and the discrepancy between the products of adenosine phosphate-isopentenyltransferase (IPT) and the substrate preferences of subsequent reactions. Recent gene discoveries related to lonely guy (LOG)-independent pathways suggest a spatial extension of cytokinin biosynthesis into the apoplast. Other intriguing issues remain to be addressed, such as elucidating the synthetic pathway for cis-zeatin and unraveling the molecular mechanisms governing selective substrate use by the cytokinin biosynthetic enzyme Tumor morphology root (Tmr) from the phytopathogen Agrobacterium tumefaciens. Further studies are needed to reveal a fully comprehensive picture of cytokinin metabolism.
细胞分裂素是一类植物激素，通过涉及代谢和信号级联的精细调节反馈回路，在调节植物生长和应激反应中发挥关键作用。在过去25年里，研究已经确定了参与细胞分裂素生物合成和失活途径的关键基因。然而，我们的理解仍存在一些空白，特别是关于亚细胞区室之间中间代谢物的移动，以及磷酸腺苷 - 异戊烯基转移酶（IPT）的产物与后续反应的底物偏好之间的差异。最近与不依赖孤独蛋白（LOG）途径相关的基因发现表明，细胞分裂素生物合成在空间上扩展到了质外体。其他有趣的问题仍有待解决，例如阐明顺式玉米素的合成途径，以及揭示植物病原体根癌农杆菌的细胞分裂素生物合成酶肿瘤形态根（Tmr）控制选择性底物利用的分子机制。需要进一步的研究来全面揭示细胞分裂素代谢的全貌。
