控制水稻穗型的遗传网络解析

Panicle architecture that constitutes of panicle size, number of primary and secondary branch, grain number and etc., are key determinants of grain yield in rice production. Panicle formation includes the processes of floral organ initiation, differentiation, and development, and requires the involvement of multiple genes. Therefore, panicle architecture is a canonical complex quantitative trait. Although several key genes that control panicle architecture have been cloned, those available for panicle engineering are still very limited. The genetic network of panicle architecture control in the main cultivars remains unknown. In this study, we plan to collect major cultivated varieties that bear big panicle size in the region of Yangtze river and analyze the genetic structure for panicle architecture in these varieties based on genome resequencing and panicle transcriptome analyses. The gene interacting network for panicle architecture will be established. Through identification of novel genes and integration of varied genetic pathways, the new mechanism and major regulatory network involved in panicle formation will be elucidated. In addition, the elite varieties for different ecological regions will be developed by introducing some natural variations of key genes for panicle formation into the rice major cultivars. This study will shed lights on understanding the elaborate regulatory network of panicle architecture control in the rice major cultivars and will be benefit for crop molecular breeding.

穗型是决定水稻产量的重要性状，可分解为穗长、一二次枝梗数目及穗粒数等。穗型形态建成涉及花器官起始、分化和发育等诸多生理生化过程，因而穗型是典型的多基因控制的复杂数量性状。尽管已有一些关键的穗型控制基因被克隆，然而有育种价值的穗型控制基因仍为数很少，尤其是主栽品种中穗型的遗传调控网络仍不清楚，制约了穗型的分子改良进程。本研究拟围绕长江流域大穗型主栽品种，揭示其穗型的遗传结构特征和基因互作网络；通过对水稻穗型新的关键基因的发掘和与已知穗型调控的整合，揭示调控穗型发育的新机制，提出新的穗型遗传调控网路；以主栽品种为底盘培育穗型优异的水稻新种质/新材料，研究主效穗型遗传网络及其区域适应性，为水稻高产优质分子设计育种提供理论依据和新的基因资源。

穗型是决定水稻产量的重要性状之一。由于遗传力弱，目前鉴定的具有育种价值的穗型控制基因仍为数很少，主栽品种中穗型控制遗传网络尚不清楚。本研究围绕这一科学问题，通过两年的项目实施，发现长江流域水稻主栽品种中穗型控制具有品种特征性，即长期的驯化使得主栽品种形成了与其遗传结构相吻合的穗型调控网络；通过在不同品种中进行幼穗期的转录组测序，结合编辑穗型关键控制基因，扰动其穗型形成的调控网络，阐释了关键穗型控制基因的互作网络；发现了关键穗型控制基因Gn1a在主栽品种中的8种等位变异，创制了3种新的变异类型，揭示了调控抽穗期的重要基因Hd1在历年品种中的19种单倍型及功能，以及明确及创制了IPA1和dep1的多种单倍型；完成了4个新的穗型调控基因的分子机制解析；以Hd1为核心进行了单倍型和穗粒数关联分析，发现籼稻中主要的Hd1单倍型能改善粳稻穗型及产量，阐明了HD1在水稻主栽品种的区域适应性；产生了一批具有育种价值的高产新品种和新材料，5个品种通过了国家或地方审定，4个新品种申报品种权。研究成果为水稻主栽品种中穗型遗传调控网络突破性进展的取得和超高产水稻的分子设计育种奠定材料基础，提供了理论指导。