赤霉素调控植物侧生器官发育的分子机理研究

The phytohormones gibberellins regulate many plant developmental processes, including seed germination, stem elongation, flowering, It is now accepted that GA function by controlling cell proliferation and cell elongation. Plant established and modified the main body plan throughout the entire lifecycle by controlling axillary organ formation, however, it is unclear whether gibberellin participate in this process. Here, we demonstrate that GAs regulate axillary shoot branching as well as the casually mentioned development processes. The axillary branch numbers of GA-deficient mutant ga1-3 was much more than that of the wild type plantlet, while gai-t6 rga-t2 rgl1-1 rgl2-1 that lacing four DELLA proteins established only one main flowering stem with no axillary branch. So we concluded that the DELLA-dependent component controls the axillary branch development. The molecular nature remains elusive, but clue from Stigolactone is helpful in solving this problem. Strigolactone is an new finding plant hormone which play important role in controlling axillay bud outgrowth. In this project, we plan to examine the genetic interaction between gibberellins and strigolactones, besides that, we will focus on GIP12 which interacted with DELLA protein and expressed specifically in shoot meristem. We plan to provide a better understanding of the mechanisms how gibberellins regulate axillary branch development.

赤霉素是一种重要的植物激素，通过控制细胞分裂和分化调控植物生长发育。赤霉素合成途径突变体ga1-t，赤霉素受体gid1agid1c突变体以及DELLA蛋白积累gai突变体的侧枝明显增多，而DELLA蛋白缺失突变体gai-t6 rga-t2 rgl1-1 rgl2-1的侧枝数目减少，表明赤霉素在植物侧生器官的生长发育过程中也起着重要作用，但是赤霉素是如何调控侧生器官发育的分子机制尚不清楚。本项目针对这一科学问题开展研究。利用遗传学手段分析赤霉素调控侧枝数目是否依赖于独角金内酯这一调控侧枝伸长的关键激素。另外， 前期研究发现与DELLA蛋白互作的GIP12可能参与侧生器官发育，过量表达GIP12的转基因拟南芥植株的侧枝数目明显增加。在此基础上，本项目拟探寻DELLA蛋白与GIP12共同的靶基因，深入研究赤霉素调控植物侧生器官发育的分子机制。

赤霉素是一种重要的植物激素，通过控制细胞分裂和分化调控植物生长发育。赤霉素参与调控植物多个器官的发育调控，但是目前还没有文献报道其在植物侧生器官发育中的作用。我们研究发现，赤霉素参与调控拟南芥侧枝发育。赤霉素合成途径突变体ga1-t，赤霉素受体gid1agid1c突变体以及DELLA蛋白积累gai突变体的侧枝明显增多，而DELLA蛋白缺失突变体gai-t6 rga-t2 rgl1-1 rgl2-1的侧枝数目减少，表明赤霉素在植物侧生器官的生长发育过程中扮演着重要作用；独脚金内酯是调控植物侧枝发育的重要激素，目前尚不清楚赤霉素在调控侧枝发育上是否依赖于独脚金内酯。通过荧光定量PCR分析发现，DELLA蛋白并非通过调节根部独脚金内酯的合成影响分枝数目，另外嫁接实验基本排除了独脚金内酯SLs在赤霉素调控侧枝发生中的作用。茎尖分生区重要基因的表达水平在赤霉素缺陷型突变体及DELLA蛋白积累型突变体中发生了较大变化，暗示赤霉素可能是通过调节KNAT2、BP1和STM等基因的表达水平来实现对侧枝发育的调控作用。