水稻产量基因qGWP9的功能和分子机制研究

Identification of excellent genetic resources is the basis of yield breakthrough in rice. Grain yield in rice is a complex quantitative trait multiplicatively determined by its three component: number of panicles, number of grains per panicle, and grain weight. The yield gene qGWP9 (grain weight per plant) that was fine-mapped and isolated from the population of the high-yielding hybrid rice, Liangyoupeijiu, was used in this study. Sequencing showed the third exon of the qGWP9 gene was deletion of 13 bp nucleotides in 93-11, and that of Peiai 64s was not missing. So we obtained the candidate gene of the target gene, encoding a containing 135 amino acid protein related to cell division. By amplification of the full-length cDNA and research of function of different segments, to clear qGWP9 gene structure; to construct vectors of functional complementation and interference for understanding of the gene function; to build the GUS and GFP vectors to conduct tissue-specific expression analysis and observation of subcellular localization of qGWP9; to analyze the relationship between the gene qGWP9 and other yield genes IPA1, Gn1, DEP1 and GW2; to dissect the network system of the molecular regulation of network system in panicle and grain development, which is beneficial to providing a theoretical support for clarification of the molecular mechanism of high yield in rice.

优异基因资源的发掘是实现产量突破的基础，而产量是一个由穗数、每穗粒数和粒重产量三因子共同作用的复杂数量性状。本申请利用高产杂交稻两优培九群体中已精细定位和分离的qGWP9单株重- - 产量基因，测序发现93-11在该基因的第三个外显子缺失了13 bp的核苷酸，而培矮64s未缺失，从而获得了目标基因的候选基因，目的基因编码一含135个氨基酸的蛋白，与细胞分裂有关。我们将通过全长cDNA的扩增及对不同区段功能的研究，明确qGWP9基因结构；构建功能互补、干涉等载体研究该基因的功能；构建GUS、GFP载体，进行qGWP9组织特异性表达分析及亚细胞定位观察；并初步分析qGWP9基因与其他产量基因IPA1、Gn1、DEP1和GW2的作用关系，剖析在穗和籽粒发育中的分子调控网络体系，为明确其对水稻产量形成的分子机制提供理论支撑。

该项目利用迟抽穗高产突变体GHD10（qGWP9），遗传分析发现该突变表型受隐性单基因控制。我们利用图位克隆法克隆了qGWP9，该基因编码一个Cys-2/His-2 锌指结构转录因子，为核定位蛋白，主要在叶片和穗表达。通过调节成花诱导途径基因的表达，调控株高和穗部发育，以及粒重和产量。细胞水平分析发现qGWP9促进细胞分裂、使得稻穗变密、枝梗数增加和每穗粒数增多，从而促进水稻增产。再利用我国的稻种资源，发掘了3个qGWP9等位基因qGWP9-1（GHD10）、qGWP9-2和qGWP9-3。来自qGWP9-2显性等位基因可使两优培九亲本9311增加20%以上的千粒重和10%以上的产量。基因的调控网络还在进一步研究。还利用多个产量基因（GHD10-GS2-DEP1-IPA1）聚合研究，分析了基因聚合效应，并设计了高产基因的聚合育种模型。还在杭州举办了小型国际学术会议。在《Rice》和《National Sci. Review》等期刊发表论文8篇，授权专利1项，培养博士生3名，硕士生3名。