BRASSINOSTEROID SIGNALING IN ARABIDOPSIS

植物对光的反应能力对它们的生存至关重要。最近有证据表明油菜素类固醇(BRS)与光反应有关，这使得油菜素类固醇反应成分的鉴定引起了人们的极大兴趣。不能合成BR的幼苗即使在黑暗中生长也会像光照植物一样发育。此外，这些突变体揭示了BRS在整个发育过程中的重要作用。试图识别BR反应和信号通路组件的传统筛查因未能发现除BRI1基因以外的所有基因突变而受到阻碍。对于为什么在这些筛查中只发现了一个基因，有几种解释是可能的。其中最有可能的两种情况是，BR反应所需的基因参与了其他途径(从而产生了与BR合成突变体不同的表型)和/或这些基因是多余的或对生存是必要的。我将使用新的方法来绕过这些障碍，并确定BR信号的新组件。在第一种方法中，对不同的拟南芥生态型进行数量性状基因座分析将使我能够首先定位并克隆新的BR反应元件。其次，BR：生长素在拟南芥中的协同作用将为BR研究开辟一个新的生态位。这个荷尔蒙途径之间的交流的显著例子为更好地理解每种荷尔蒙单独的信号以及它们之间的交叉点提供了一个机会。

Plants' ability to respond to light is crucial for their survival. Recent evidence implicating brassinosteroids (BRs) in the light response has made the identification of brassinosteroid response components of great interest. Seedlings unable to synthesize BRs develop as light-grown plants even when grown in darkness. Moreover, these mutants reveal a significant role for BRs throughout development. Traditional screens attempting to identify components of the BR response and signaling pathway have been hampered by failure to uncover mutations in all but one gene, BRI1. Several explanations for why only one gene was identified in these screens are possible. Two of the most likely are that the genes required for BR response are involved in other pathways (thus yielding phenotypes distinct from BR synthetic mutants) and/or that these genes are redundant or essential for viability. I will use novel approaches to circumvent these obstacles and identify new components of BR signaling. In the first of these approaches, quantitative trait loci analysis on disparate Arabidopsis ecotypes will allow me to first localize and then clone new BR response elements. Secondly, characterization of BR: auxin synergy in Arabidopsis will define a new niche of BR research. This striking example of communication between hormone pathways presents an opportunity to better understand the signaling of each hormone alone as well as the nodes of intersection between them.