性二态普遍存在于具有性别分化的物种中，但植物的性二态特征表现通常不如动物的明显，因而较少被关注，植物性二态的形成机制也不甚明确。苦草是水媒传粉的雌雄异株沉水植物，对维持水体生态系统稳定具有重要作用。本项目以生活史上差异明显的苦草和刺苦草为对象，采用种群调查结合控制实验的方法，检测不同水位下的种群性比，以及雌、雄植株的生长、繁殖、生理表现、资源分配式样，分析性二态特征表现动态及其与种群性比的关系；采用分子标记检测雌、雄亚群体的遗传变异性，探讨性二态、种群性比对种群遗传结构的影响；运用组学技术分析不同发育时期的雌、雄个体的基因表达差异及其变化，寻找与性别分化及性二态相关的基因或信息位点，探讨性二态的分子基础；通过设计实验来检验与性二态相关的理论与假设；通过综合分析来阐明苦草属性二态的形成机制及生态适应性。本项目将促进我们对植物性二态机制的认识和利用苦草的水体生态系统修复实践.。

Sexual dimorphism is common phenomenon in dioecious species, but the characterisitics related to sexual dimorphism in plant species is usually subtle and has attracted few attentions, consequently the mechanism underlying sexual dimorphism in plants is still not well elucidated, especially for aquatic plants. Although the genus Vallisneria is characterized as water-pollinated, dioecious, submerged plants with remarkable sexual dimorphic features and plays important role in maitaining the stability of water ecosystem, the evolutionary mechanism and ecological adaptation of its sexual dimorphism remain unknown. With two Vallisneria species, V. natans and V. spinulosa, that present numerous differences in life history strategies and reproductive habits as targent plants, the project is designed to do the following researches: 1) Common garden experiments and field population inversitgations will be conducted to compare the perfomance of sexual dimorphism and sex ratios of populations among species and their responses to water level fluctuation; 2)By using SSR assays, we will compare genetic diversity levels between male and female subpopulations to understand the efffects of sexual dimorphism and sex ratio bias on population structure at fine scale; 3)We will adopt next generation sequecing method to compare trancriptome informations between female and male individuals.under different water levels to find out the potential genes or loci that determine or link with sex and sexual dimorphism;4)We will design corresponding expriments to test the existing hypotheses related to sexual dimorphism respectively,and try to reveal the mechanism and ecological adaptation of sexual dimorphism in Vallisneria. This project will not only improve our knowledge of sexual dimorphism in dioecious plants, but also provide guidance to practical applications such as using Vallisneria to ecologically restore water ecosystems.