高温影响水稻不同Wx等位基因表达及直链淀粉含量的分子机制研究

During rice grain filling stage, the high temperature is an important factor which can affect grain quality, especially the starch composition and structure. Therefore, it is an important research direction to study the regulation mechanism of rice grain starch quality responding to high temperature, which will contribute to generate rice cultivars with steady high quality. The Wx gene is the key genetic factor controlling amylose content in rice grain, which are one of the most important determinants of rice grain quality. There are several alleles of Wx gene in rice, and their expression as well as the amylose content has been reported to be affected by the environmental conditions including high temperature during grain filling. But, the molecular regulation mechanism is not clear. In this project, a series of near-isogenic lines (NILs) carrying different Wx alleles (Wxa，Wxb，Wxin，Wxmw，Wxlsv，wx) and transgenic rice lines with different site-directed mutations in the Wx gene will be used. All the materials will be treated with high temperature at filling stage, and systematical analyses will be carried out to compare for the similarities and differences of rice grain quality and Wx allele’s expressions responding to different temperature. On this basis, we will further investigate the molecular regulation mechanism of Wx allele’s expressions responding to high temperature by technologies including site-directed mutation, expression in vitro and DNA methylation. These results will reveal the molecular regulation mechanism of high temperature influencing on Wx expression and amylose content, and provide theoretical basis to breed high temperature-insensitive rice variety with high quality.

灌浆结实期高温是影响稻米品质的重要因素，因此研究高温条件下稻米淀粉形成过程的调控机制是培育具有稳定优质性状的水稻品种的一个重要研究方向。Wx基因是控制直链淀粉含量的关键基因，也是稻米品质改良的重要研究对象。Wx基因表达易受温度等环境因素的影响，是影响稻米品质的重要因素。本项目以已经创建的具有不同Wx等位基因的近等基因系（Wxa，Wxb，Wxin，Wxmw，Wxlsv，wx）、以及Wx人工突变转基因水稻为材料，在灌浆结实期进行高温处理，系统分析携带不同Wx等位基因近等基因系材料在稻米品质、目的基因表达特性等方面对高温响应的异同；在此基础上，借助定点突变与体外表达、DNA甲基化水平检测等技术，深入解析不同Wx等位基因表达对高温响应的分子调控机制。通过研究，期望能阐明高温影响Wx基因表达和直链淀粉含量的分子机制，进而为高温钝感性优质水稻材料的培育提供理论和实践依据。

灌浆结实期高温是影响稻米品质的重要因素，因此研究高温条件下稻米淀粉形成过程的调控机制是培育具有稳定优质性状的水稻品种的一个重要研究方向。Wx基因是控制直链淀粉含量的关键基因，也是稻米品质改良的重要研究对象。Wx基因表达易受温度等环境因素的影响，是影响稻米品质的重要因素。本项目以已经创建的具有不同Wx等位基因的近等基因系（Wxa，Wxb，Wxlsv，Wxin，Wxmp，Wxop，wx）以及Wx人工突变转基因水稻为材料，在灌浆结实期进行高温处理，系统分析携带不同Wx等位基因近等基因系材料在稻米品质、目的基因表达特性等方面对高温响应的异同，明确了其中的规律性。利用遗传背景单一的日本晴Wx近等基因系进一步开展了相关的分子机制研究，在可变剪切调控以及甲基化调控方面取得一定的进展。同时利用多组学分析的手段宏观阐述高温对水稻籽粒中基因表达调控的影响，确定了差异表达基因，结合SSRG基因的共表达基因进一步选出用于淀粉合成调控网络研究的候选基因，并且通过CRISPR-Cas9的手段创建相关的突变材料，围绕淀粉品质形成展开基因功能研究。此外，通过多学科结合的手段（数学建模、物理化学和酶学）试图阐述水稻灌浆各时期直链和支链淀粉合成之间的相互作用以及其对高温的响应。