Department of Stem Cell Biology, University of Heidelberg, D-69120 Heidelberg, Germany.
Nature. 2010 Jun 24;465(7301):1089-92. doi: 10.1038/nature09126.
The classic phytohormones cytokinin and auxin play essential roles in the maintenance of stem-cell systems embedded in shoot and root meristems, and exhibit complex functional interactions. Here we show that the activity of both hormones directly converges on the promoters of two A-type ARABIDOPSIS RESPONSE REGULATOR (ARR) genes, ARR7 and ARR15, which are negative regulators of cytokinin signalling and have important meristematic functions. Whereas ARR7 and ARR15 expression in the shoot apical meristem (SAM) is induced by cytokinin, auxin has a negative effect, which is, at least in part, mediated by the AUXIN RESPONSE FACTOR5/MONOPTEROS (MP) transcription factor. Our results provide a mechanistic framework for hormonal control of the apical stem-cell niche and demonstrate how root and shoot stem-cell systems differ in their response to phytohormones.
经典的植物激素细胞分裂素和生长素在维持嵌入茎和根分生组织中的干细胞系统中发挥着重要作用，并表现出复杂的功能相互作用。在这里，我们表明，这两种激素的活性都直接集中在两个拟南芥反应调节因子（ARR）基因的启动子上，即 ARR7 和 ARR15，它们是细胞分裂素信号的负调节剂，并且具有重要的分生组织功能。虽然 ARR7 和 ARR15 在茎尖分生组织（SAM）中的表达受细胞分裂素诱导，但生长素具有负效应，至少部分是通过生长素反应因子 5/单胚（MP）转录因子介导的。我们的研究结果为激素对顶端干细胞生态位的调控提供了一个机制框架，并展示了根和茎干细胞系统对植物激素的反应有何不同。
