HSR1抑制高温胁迫下稻米垩白形成的分子机制研究

垩白易造成稻米外观品质变差，影响稻米加工品质和市场价值，而高温胁迫是加剧垩白形成的主要因素。在前期研究中，申请人从粳稻日本晴遗传背景下筛选到一个高温胁迫下稻米低垩白突变体hsr1，其表现为高温胁迫后垩白粒率和垩白度均显著低于野生型。本申请在获得HSR1候选基因并完成转基因互补验证的基础上，拟进一步开展系列功能表达载体构建及遗传转化，明确HSR1的组织和时空表达特征，以及抑制高温胁迫下稻米垩白形成的生理响应途径；开展温度梯度处理后叶绿体等细胞器编码基因转录后修饰分析，明确HSR1对细胞器基因转录后修饰在调控高温胁迫下稻米垩白形成中的作用；开展互作蛋白或细胞器编码基因RNA转录本筛选与鉴定，结合遗传双突变体构建、RNA结合蛋白免疫沉淀和凝胶阻滞实验，阐明HSR1抑制高温胁迫下稻米垩白形成的遗传机制，并利用核心种质资源，进行HSR1等位基因型鉴定，探索其在高温低垩白优质稻米分子设计育种中的前景。

Chalkiness leads to the deterioration of grain appearance quality, which affects grain processing quality and commodity value in rice. And high temperature stress is the main factor aggravating grain chalkiness formation. In previous study, from the Nipponbare mutant library, we obtained a low chalkiness mutant hsr1 (high-temperature stress response 1) which shows that the chalky grain rate and the chalkiness degree was significantly lower than that of the wild type after high temperature stress treatment. Based on map-based cloning of HSR1 candidate genes and transgenic complementation verification, we will further carry out series of functional expression vector construction and genetic transformation to clarify the specificity of temporal and organization expression of HSR1, as well as the physiological response pathway to inhibit chalkiness formation under high temperature stress. We will develop the post-transcriptional modification analysis of organelle coding genes after temperature gradient treatment to clarify the role of post-transcriptional modification of the organelle genes by HSR1 in regulating rice chalkiness formation under high temperature stress. Meanwhile, we will carry out screening and identification of interaction proteins or organelles coding RNA transcriptions of HSR1. Then we will illustrate the effect of HSR1 inhibiting the rice chalkiness formation under high temperature stress with the construction of the genetic double mutant, RNA binding protein immunoprecipitation and electrophoretic mobility shift assays (RNA-EMSA) results. Finally, we will identify the alleles of HSR1 in conventional core germplasm resources to explore its application prospect in molecular design breeding in high quality rice.