一个全新的水稻淀粉合成相关基因Flo7的图位克隆和功能研究

Rice (Oryza sativa L.) seeds contain great amount of starch. The accumulation of starch contribute directly to the yield formation, the composition and Physical-chemical properties of starch also determine the appearance and eating quality of rice, therefore, in-depth study of starch synthesis pathway is of great importance for improving the yield and quality of rice. The pre-project study discovered a mutant defected in starch synthesis, leading to a floury opaque endosperm appearance. By positional cloning, the mutant gene has been localized in a 101kb region in chromosome 10, which contains no reported genes related to starch synthesis. So the mutant is a novel floury endosperm mutant (named flo7) in rice, is expected to reveal a novel starch biosynthesis regulatory pathway. Cloning and functional analysis of the Flo7 gene, together with the detailed characterization of flo7 mutant phenotype by using of genetics, molecular biology, biochemistry, cell biology techniques, will help us clarify the function of Flo7 gene in the starch synthesis pathway in rice.

水稻（Oryza sativa L.）籽粒中含有大量淀粉，灌浆过程中淀粉的积累不仅直接贡献了产量的形成，淀粉的组成、理化性质还决定了稻米的外观和食味品质，因此，深入研究淀粉合成途径对于提高稻米产量和品质具有重要意义。本项目前期发现了一个胚乳中淀粉合成过程异常的突变体材料，其成熟胚乳显示出粉质不透明的外观。通过图位克隆，现已将突变基因定位于第10染色体101kb的区间内，该区域内不含有已经报道的淀粉合成相关基因，因此，该材料是一个全新的水稻粉质胚乳突变体，将之命名为flo7突变体。本项目拟综合运用遗传学、分子生物学、生物化学、细胞生物学等技术手段，分离Flo7基因，并对该基因进行功能分析，同时对flo7突变体的表型进行深入研究，以期阐明该基因在水稻淀粉合成途径中的功能。

本项目以一个全新的水稻(Oryza sativa L.)粉质胚乳突变体flo7为研究材料，旨在克隆其中突变基因并阐明该基因在籽粒发育过程中的作用机理。研究结果显示，flo7突变体籽粒淀粉粒松散，直链淀粉含量下降，支链淀粉链长也发生较大改变，并且粒形也发生了变化。Flo7基因编码水稻丙氨酸氨基转移酶，该基因在水稻中呈组成型表达。FLO7蛋白定位于细胞质中。该基因的突变能够引起众多淀粉合成相关酶类的表达量的改变，进而影响水稻籽粒淀粉的合成和沉积。此外，过表达Flo7基因能够显著提高种子千粒重。综上，本研究可为水稻品质及产量的提供理论依据。