水稻粒型基因的遗传效应及其调控网络解析

Elucidateing formation and molecular regulation mechanism of rice grain size were the theoretical basis for the molecular design breeding in rice high-yield . The GW2, GS3, qGL3, GS5, GW5, GW8 and other granular genes were cloned from different research materials and controlled by the different regulatory mechanism，so their genetic effect could not be directly compared. Applicants bred a large grain germplasm TD70, a single grain weight up to 70mg，containing at least six grain weight increased gene (large-grain type). In this project，we used 6 kinds of isogenic lines at the background of Kasalath and their derived population to explain grain gene molecular regulation，build a database about of different large grain genes combinations and their generating genetic interaction effects, joint analysis RNA-seq of 6 isogenic lines and their derived population, induct different expression level differences of the same genes in different genes combinations and the common expression differences genes ， establish the corresponding links of genotype and phenotype, elucidate the genetic regulatory networks about different large grain genes combinations ,evaluate large grain breeding value by method of hybrid introduction on the base of identifying grain genes haplotype of the main varieties and major backbone parents and testing phenotype of them. Our study systematically evaluated the combined effects of 6 cloned genotypes and laid the foundation for the breeding and utilization of the grain genes.

解析粒型基因的遗传效应和调控网络，是水稻高产分子设计育种的理论基础。克隆的GW2、GS3、qGL3、GS5、GW5、GW8等粒型基因源于不同的遗传材料，分子机制也不完全相同，难以直接比较各自的遗传效应。申请者育成一个单粒重达70mg的特大粒种质TD70，至少含有上述6个粒重增加型（大粒型）基因。本项目利用一套源于TD70大粒型基因的籼稻Kasalath（含相应的小粒型基因）为背景的6个大粒型基因等基因系及互相杂交的衍生群体为研究材料，分析上述基因的遗传效应及两两之间互作效应，建立遗传效应数据库；联合等基因系和衍生群体混合样本的RNA-seq分析，解析不同粒型基因模式下的水稻籽粒形成遗传调控网络；同时分析生产上主推品种和骨干亲本的粒型基因单倍型和表现型，杂交导入验证大粒型基因的遗传效应。本研究结果将系统评价6个已克隆的粒型基因间的组合效应，为粒型基因的育种利用奠定基础。

开展水稻粒型基因的研究对提高水稻产量和稻米品质具有重要意义。已经克隆GW2、GS3、qGL3、GS5、GW5、GW8等粒型基因源于不同的遗传材料，分子机制也不完全相同，准确鉴定粒型单基因遗传效应，解析多基因互作遗传调控网络解析难度较大。项目以含来源于特大粒种质TD70的GW2、GS3、qGL3等6个表现为增效作用的粒型基因的Kasalath背景的单基因、双基因近等基因系为材料，对粒型基因的遗传效应进行了分析，得出GW2-T主要影响粒宽和粒厚，GS3-T和qGL3-T对粒长作用较大；对TD70，Kasalath，以及以Kasalath为背景的qGL3，GS3，GW2的单基因近等基因系，双基因近等基因系不同发育时期的幼穗进行RNA-seq分析，研究这三个粒型基因在水稻小穗发育阶段对粒型发育调控的表达特征和调控网络途径，同时利用亲本以及双基因近等基因系研究这三个基因间的互作以及调控关系，明确了大粒基因籽粒发育的调控。利用NIL-GS3和NIL-gs3材料，对其成熟籽粒的粒型性状进行考察，明确了GS3的遗传效应；对不同发育阶段的幼穗进行转录组测序，分析了水稻幼穗发育过程中GS3基因水稻籽粒发育通路上相关基因的变化规律；利用GW2、GS3等6个已报道粒型基因的分子标记或测序分析172份不同生态类型的主推和骨干粳稻品种中粒型基因的基因型及遗传效应，系统评价了6个已克隆的粒型基因间的组合效应。研究结果为粒型基因的分子设计育种利用奠定基础。