籼型与粳型杂草稻的遗传分化及其进化驱动机制

杂草稻是限制水稻优质高产的世界级稻田恶性杂草，同时也是水稻育种的重要基因资源，揭示其多样性形成与维持机制对杂草防治和基因资源利用均至关重要。在籼稻与粳稻种植区，出现了籼型和粳型杂草稻的遗传分化，但对其分化机制尚不清楚。近年来更多粳型杂草稻出现在籼稻改粳稻的种植区，其遗传变异也不断增加，这些粳型杂草稻的形成方式与进化驱动却无报道。针对上述问题，项目组将开展如下研究：1）揭示杂草稻籼-粳遗传分化规律及其空间分布式样；2）利用叶绿体、核基因组DNA序列及种子落粒基因多态性，研究去驯化过程对新产生粳型杂草稻起源与进化的影响；3）利用叶绿体与核基因组DNA序列及特有指纹，研究栽培稻基因渐渗对杂草稻籼-粳遗传分化以及多样性形成的驱动作用。上述研究结果不仅有助于我们理解基因突变与杂交渐渗等因子对杂草稻起源、进化及多样性形成的驱动作用，而且还有利于制定杂草稻有效防治策略以及杂草稻基因资源的合理挖掘与利用。

Weedy rice is a noxious weed that infests worldwide rice fields and causes tremendous losses of rice yield and quality. But on the other hand, weedy rice harbors important germplasm for rice breeding. Understanding the origin and maintenance of genetic diversity in weedy rice is critical both for effective weedy rice control and germplasm utilization. In indica and japonica rice-planting regions, indica-types and japonica-types of weedy rice have been evolved. However, knowledge of the underlying mechanisms of such genetic differentiation is limited. With the increased cultivation of japonica rice varieties toward the southern rice-planting regions, more japonica-types of weedy rice are found in the regions where indica and japonica varieties are cultivated. As a result, increased diversity is detected in these weedy rice populations. Yet, no detailed research data concerning the origins and evolutionary driving forces of such japonica-types of weedy rice have been reported. In this project, we plant to carry out the following researches to address the above questions: (1) determining indica-japonica genetic differentiation in weedy rice and its geographic distribution of the two types of weedy rice; (2) analyzing the role of rice dedomestication in the origin and evolution of japonica-types of weedy rice, comparing DNA sequences and polymorphic fingerprints from chloroplast and nuclear genomes, in addition to polymorphisms of seed shattering genes; (3) determining the role of crop-weed gene introgression in indica-japonica genetic differentiation in weedy rice, particularly in the origin of japonica-types of weedy rice, using DNA sequences and molecular fingerprints from chloroplast and nuclear gnomes. Results generated from the above studies will not only facilitate our understanding of the roles and underlying mechanisms of dedomestication and gene introgression in the origin and evolution of weedy rice, but also are useful for the design of effective strategies for weedy rice control, as well as for the efficient utilization of weedy rice germplasm in rice breeding.