Wang Ying, Wang Jin, Shi Bihai, Yu Ting, Qi Jiyan, Meyerowitz Elliot M, Jiao Yuling
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, National Center for Plant Gene Research, Beijing 100101, China Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125.
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, National Center for Plant Gene Research, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Cell. 2014 May;26(5):2055-2067. doi: 10.1105/tpc.114.123083. Epub 2014 May 21.
Plants differ from most animals in their ability to initiate new cycles of growth and development, which relies on the establishment and activity of branch meristems harboring new stem cell niches. In seed plants, this is achieved by axillary meristems, which are established in the axil of each leaf base and develop into lateral branches. Here, we describe the initial processes of Arabidopsis thaliana axillary meristem initiation. Using reporter gene expression analysis, we find that axillary meristems initiate from leaf axil cells with low auxin through stereotypical stages. Consistent with this, ectopic overproduction of auxin in the leaf axil efficiently inhibits axillary meristem initiation. Furthermore, our results demonstrate that auxin efflux is required for the leaf axil auxin minimum and axillary meristem initiation. After lowering of auxin levels, a subsequent cytokinin signaling pulse is observed prior to axillary meristem initiation. Genetic analysis suggests that cytokinin perception and signaling are both required for axillary meristem initiation. Finally, we show that cytokinin overproduction in the leaf axil partially rescue axillary meristem initiation-deficient mutants. These results define a mechanistic framework for understanding axillary meristem initiation.
植物在启动新的生长和发育周期的能力方面与大多数动物不同，这依赖于具有新干细胞龛的侧生分生组织的建立和活动。在种子植物中，这是通过腋生分生组织实现的，腋生分生组织在每个叶基部的叶腋处形成并发育成侧枝。在这里，我们描述了拟南芥腋生分生组织起始的初始过程。通过报告基因表达分析，我们发现腋生分生组织从生长素水平低的叶腋细胞开始，经过典型的阶段。与此一致的是，叶腋中生长素的异位过量产生有效地抑制了腋生分生组织的起始。此外，我们的结果表明，生长素外流是叶腋生长素最低水平和腋生分生组织起始所必需的。在生长素水平降低后，在腋生分生组织起始之前观察到随后的细胞分裂素信号脉冲。遗传分析表明，细胞分裂素的感知和信号传导对于腋生分生组织的起始都是必需的。最后，我们表明叶腋中细胞分裂素的过量产生部分挽救了腋生分生组织起始缺陷型突变体。这些结果定义了一个理解腋生分生组织起始的机制框架。
