叶直立性是与水稻产量密切相关的重要株型性状，但是调控叶直立性的细胞学机制及其遗传调控网络还很不清楚。我们通过筛选叶倾角对油菜素甾醇不敏感的突变体和图位克隆，发现RLA1是一个调控叶片直立性并参与油菜素甾醇信号转导的新基因，并且RLA1与水稻中的BR信号转导组分OsGSK2和OsBZR1互作。此外，通过分析叶枕特异的转录组，我们发现一个基因X可以作为叶枕发育的分子标记。本项目将在前期研究基础上，利用组织切片和叶不同发育时期的叶枕特异转录组，阐明叶枕发育的细胞学过程和基因表达调控网络；采用多种现代生物学的方法，研究RLA1及其互作基因参与BR信号转导并调控叶枕发育的遗传、细胞和生化机制。该研究将完善水稻中独特的BR信号转导通路；阐明RLA1及其互作基因控制水稻叶枕发育的细胞学机制及其遗传和生化网络；为塑造水稻的理想株型并提高产量提供理论依据。

Leaf erectness is an important trait to determine rice plant architecture and grain yield, but the underlying cellular and molecular mechanisms that regulate leaf erectness development remain big mysteries. Through genetic screening for brassinosteroid-insensitive rice mutants in lanima inclination and map-based cloning, we identified RLA1 as a novel gene involved in the BR signaling pathway, and it can physically interact with the BR signaling components OsGSK2 and OsBZR1. In addition, by analysing the genes specifically expressed in the lamina joints, we found a X gene can be used as a tissue-specific molecualr marker of the lamina joint development. In this proposed study, we plan to investigate the cytological structure and gene regulatory networks in the leaf joint at different developmental stages. Using various modern biology approaches, we will investigate how RLA1 participates the BR signaling and what are the genetic, cellular and biochemical mechanisms of leaf joint development. This study will greatly enhance our understanding on the specific BR signaling pathway in rice and disclosure the cellular mechanism and genetic and biochemical network that RLA1 and it’s interactors regulate leaf joint development, which can provide the theoretical basis to create ideal plant architecture and increase grain yield in rice and other cereal crops.