独角金内酯调控水稻分蘖芽休眠与萌发转换的机理

Chemical control of the ineffective tillering in high-yield rice cultivation has been studied enthusiastically recent years. Conversion of dormancy and germination of rice tiller bud determines the appearence of rice tillering and this process has been identified to be regulated by a series of hormones and related genes. The applicants clearly illustrated the regulatory roles of auxin and cytokinin during the conversion process of rice tiller bud dormancy and germination in National Fund Projects (Hormonal changes and gene expression during conversion process of rice tiller bud germination and dormancy) in 2011. Strigolactones are a newly discovered class of hormone precursors and have been shown to be involved in the regulation of rice tillering. However, the regulation mechanisms and signal transduction pathways of strigolactones are still unclear. This study focus on the content changes of strigolactones as well as the expression level of genes related to synthesis or signal transduction of strigolactones during the conversion process of tillering bud dormancy and germination. Furthermore, this research will evaluate the effects of GR24 on the content changes of strigolactones, cytokinin and auxinthe as well as the expression changes of related genes and proteins. Results would clarify the relationship of strigolactones, cytokinin and auxin as well as the expression changes of hormone related genes. This study would further illustrate the molecular mechanisms and signal transduction pathways of strigolactones during rice tillering and provide the theoretical basis for the chemical control of rice tillering.

化学控制无效分蘖是水稻高产栽培的研究热点和努力方向，分蘖芽休眠与萌发转换决定了分蘖是否发生，而该过程受激素和相关基因表达的调控。申请者2011年国家基金课题（水稻分蘖芽萌发与休眠转换过程中的激素变化和基因表达）已明确生长素和细胞分裂素参与了分蘖芽休眠与萌发转换的调控，独角金内酯是最近才被发现的一种激素或前体，已被证明参与了水稻分蘖的调控，但其调控机理和信号转导途径尚不清楚。本研究将在前一国家基金课题的基础上，深入研究水稻分蘖芽休眠与萌发转换过程中独角金内酯的变化及其合成或信号转导相关基因的表达，研究GR24对独角金内酯、细胞分裂素、生长素及相关基因和蛋白表达的影响，明确分蘖芽休眠与萌发转换过程中内源独角金内酯、细胞分裂素、生长素三者之间的联系及其激素合成相关基因的表达，阐明独角金内酯调控水稻分蘖发生的分子机理和信号转导途径，为化学调控水稻分蘖发生提供理论依据。

水稻分蘖是否发生是分蘖芽萌发与休眠转换的结果，控制无效分蘖发生对塑造高质量群体具有重要意义。本研究采用外源激素、氮素、磷素和去穗等方法诱导水稻分蘖芽萌发与休眠转换，研究了分蘖芽及着生节内源激素含量及相关基因表达的变化，明确了水稻分蘖芽休眠与萌发转换过程中独角金内酯、细胞分裂素、生长素三者之间的关系及临界比值，解析了独角金内酯对细胞分裂素、生长素及其相关基因表达的影响。探究了外施GR24对抑制水稻分蘖的效果和作用方式，解析了GR24对内源独角金内酯、细胞分裂素、生长素和相关基因表达的影响。研究结果，阐明了内源独角金内酯和外源GR24抑制水稻分蘖的分子机理和信号转导途径，为采取化学手段调控水稻分蘖提供了理论基础。