Systemic transport of trans-zeatin and its precursor have differing roles in Arabidopsis shoots
Systemic transport of trans-zeatin and its precursor have differing roles in Arabidopsis shoots
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DOI：
10.1038/nplants.2017.112
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发表时间：
2017-08-01
期刊：
影响因子：
18
通讯作者：
Sakakibara, Hitoshi
中科院分区：
文献类型：
--
作者：
Osugi, Asami;Kojima, Mikiko;Sakakibara, Hitoshi
器官间的信号传递是高等生物在代谢和形态发生过程中协调生物反应的必要条件。与动物器官相似，植物器官通过各种信号分子进行交流。其中，细胞分裂素是一类植物激素，作为根到芽的长距离信号，调节芽的各种生长和发育过程（1，2）。先前的研究已经提出，反式玉米素-核苷（一种细胞分裂素前体）是木质部导管中的主要长距离信号传导形式，其作用取决于通过作用位点附近的LONELY GUY酶进行的代谢转化（3-5）。在这里，我们报告一个额外的长距离信号形式的细胞分裂素：反式玉米素，一个积极的形式。不同的细胞分裂素生物合成和运输突变体之间的嫁接表明，根到地上部易位的trans-zeatin，木质部细胞分裂素的一个次要组成部分，控制叶的大小，但不分生组织活动相关的性状，而trans-zeatin核苷是足以调节这两个性状。考虑到木质部中的反式玉米素与反式玉米素核苷的比率以及它们响应于环境条件的递送速率变化，这种双长距离细胞分裂素信号传导系统允许植物微调枝条生长的方式以适应波动的环境。
Organ-to-organ signal transmission is essential for higher organisms to ensure coordinated biological reactions during metabolism and morphogenesis. Similar to organs in animals, plant organs communicate by various signalling molecules. Among them, cytokinins, a class of phytohormones, play a key role as root-to-shoot long-distance signals, regulating various growth and developmental processes in shoots(1,2). Previous studies have proposed that trans-zeatin-riboside, a type of cytokinin precursor, is a major long-distance signalling form in xylem vessels and its action depends on metabolic conversion via the LONELY GUY enzyme in proximity to the site of action(3-5). Here we report an additional long-distance signalling form of cytokinin: trans-zeatin, an active form. Grafting between various cytokinin biosynthetic and transportation mutants revealed that root-to-shoot translocation of trans-zeatin, a minor component of xylem cytokinin, controls leaf size but not meristem activity-related traits, whereas that of trans-zeatin riboside is sufficient for regulating both traits. Considering the ratio of trans-zeatin to trans-zeatin-riboside in xylem and their delivery rate change in response to environmental conditions, this dual long-distance cytokinin signalling system allows plants to fine-tune the manner of shoot growth to adapt to fluctuating environments.