Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, Gent, Belgium.
Development. 2010 Feb;137(4):607-17. doi: 10.1242/dev.041277.
The apical hook of dark-grown Arabidopsis seedlings is a simple structure that develops soon after germination to protect the meristem tissues during emergence through the soil and that opens upon exposure to light. Differential growth at the apical hook proceeds in three sequential steps that are regulated by multiple hormones, principally auxin and ethylene. We show that the progress of the apical hook through these developmental phases depends on the dynamic, asymmetric distribution of auxin, which is regulated by auxin efflux carriers of the PIN family. Several PIN proteins exhibited specific, partially overlapping spatial and temporal expression patterns, and their subcellular localization suggested auxin fluxes during hook development. Genetic manipulation of individual PIN activities interfered with different stages of hook development, implying that specific combinations of PIN genes are required for progress of the apical hook through the developmental phases. Furthermore, ethylene might modulate apical hook development by prolonging the formation phase and strongly suppressing the maintenance phase. This ethylene effect is in part mediated by regulation of PIN-dependent auxin efflux and auxin signaling.
暗培养拟南芥幼苗的顶端弯钩是一种简单的结构，在萌发后不久发育形成，以在通过土壤出苗的过程中保护分生组织，并且在暴露于光下时会打开。顶端弯钩的差异生长通过三个连续的步骤进行，这些步骤受到多种激素的调节，主要是生长素和乙烯。我们表明，顶端弯钩通过这些发育阶段的进展取决于生长素的动态、不对称分布，生长素的分布由 PIN 家族的生长素外排载体调节。几种 PIN 蛋白表现出特定的、部分重叠的时空表达模式，它们的亚细胞定位表明在弯钩发育过程中存在生长素流。单个 PIN 活性的遗传操作干扰了弯钩发育的不同阶段，这意味着特定的 PIN 基因组合对于通过发育阶段推进顶端弯钩是必需的。此外，乙烯可能通过延长形成阶段和强烈抑制维持阶段来调节顶端弯钩的发育。这种乙烯作用部分是通过调节 PIN 依赖性生长素外排和生长素信号传导来介导的。
