杂草稻广布于全球水稻种植区，因其遗传变异丰富、生存竞争和扩散能力强，已成为世界稻田恶性杂草，严重威胁水稻生产。揭示杂草稻遗传变异的形成和维持机制，对掌握其发生规律和有效防治极为重要。本项目组前期研究发现，在同一稻田中，分别伴生于早、晚稻的两季杂草稻群体之间产生了明显遗传分化，导致杂草稻的总体遗传多样性增加。为探索早、晚两季杂草稻群体之间的同域遗传分化及维持机制，拟开展如下研究：1）通过同质园实验，鉴定早、晚两季杂草稻群体之间的表型差异及相关生态因子；2）对典型的早、晚季杂草稻实验群体进行全基因组测序及序列分析，揭示同域遗传分化的分子基础并挖掘相关功能基因；3）对可能影响遗传分化的关键功能基因进行表达分析，确认其在实验群体中的表达差异。上述研究结果不仅有助于阐明不同生长季节杂草稻群体产生同域遗传分化的机制，有益于制定杂草稻防治策略，也为研究植物适应环境产生同域物种趋异进化提供了一种模式体系。

Weedy rice occurs in rice fields all over the world. It becomes one of the most noxious weeds in rice fields because of its abundant genetic variation and strong competitiveness and invasiveness. Therefore, weedy rice poses severe threats to the sustainable rice production. To reveal the origin and maintenance of genetic diversity in weedy rice is important for understanding the mechanisms of its infestation and damage to cultivated rice. Our previous studies indicated substantial genetic divergence between weedy rice populations that occurred in the same fields with early-season and late-season cultivated rice varieties, promoting the overall genetic diversity of weedy rice. To explore the underlying mechanisms of the sympatric genetic divergence and maintenance of the divergence between the early-season and late-season weedy rice populations, we attempted to undertake the following research activities: (1) to identify the divergence of key phenotypic traits and the ecological influences between the sympatric early-season and late-season weedy rice populations through a common-garden experiment; (2) to determine the molecular bases of sympatric genetic divergence and to identify functional genes related to the sympatric divergence through sequencing and analyses of total genomic DNA sequences between the typical early-season and late-season weedy rice individuals; (3) to confirm the functional genes that are responsible for the sympatric genetic divergence between the early-season and late-season weedy rice populations by gene expression analyses. Results from these studies will not only facilitate the revealing of the underlying mechanisms for the sympatric genetic divergence between the two seasons’ weedy rice populations, and the design of effective strategies for weedy rice control, but also provide a model system for studying the driving forces of divergent evolution adapting to different environments in plants.