慈姑属的种间生殖干扰与同种花粉优势

不同物种共享传粉者而引起传粉者竞争和种间花粉传递，在自然群落中是普遍存在的现象，并将造成种间生殖干扰。值得注意的是，被子植物特别是离生心皮类群中心皮边缘不完全融合屡见于报道，这类植物的雌蕊群在享受花粉管心皮间生长带来生殖保障的同时，也承担着异种（尤其是近缘种）生殖干扰的风险。最近在野慈姑和矮慈姑中的研究令人惊奇地发现，同种/异种花粉管都能在母本雌蕊群中生长，但异种花粉管因生长路径不同而延迟到达胚珠。这种新的同种花粉优势（CPA）机制，可能对避免种间生殖干扰发挥作用。问题在于：1）心皮边缘不完全融合是否与近缘种间的生殖干扰有直接关系？2）花粉管生长不同途径介导的CPA是否有效地避免或减轻生殖干扰？本研究以慈姑属若干代表种为材料，在调查种间花粉传递普遍性的基础上，研究近缘物种之间的传粉所带来的生殖干扰以及避免干扰的策略。

Pollinator competition and interspecific pollen transfer caused by different species sharing pollinators is a common in natural communities and would cause interspecific reproductive interference. It's worth noting that incomplete fusion of carpel margins is frequently reported in angiosperms especially apocarpous species. Although the gynoecia of these plants enjoying the reproductive assurance brought by intercarpellary pollen tube growth, also bear the risk of reproductive interference by heterospecific species (especially the relative species). Recently, in a survey of Sagittaria trifloliia and S. pygmaea, it was found that both conspecific and heterospecific pollen tubes could grow through the tissues of the gynoecium. However, conspecific pollen tubes entered into the ovules directly, whereas heterospecific tubes passed through the carpel base and adjacent receptacle tissue, to ultimately fertilize other unfertilized ovules, and the longer route taken by heterospecific pollen tubes therefore caused a delay in the time required to enter into the ovules. This is a new pattern of heterospecific pollen tube growth that occurs in apocarpous species, which may represent a novel mechanism of conspecific pollen advantage (CPA) and play an important role in avoiding interspecific reproductive interference. Here we want to know：1) Is incomplete fusion of the mature carpel directly related to the reproductive interference between relatives? 2) Is the CPA mediated by different pathways of pollen tube growth effective in avoiding or alleviating reproductive interference? In this project, we will choose the species of Sagittaria as representative plants，based on the investigation of the universality of interspecific pollen transfer, trying to figure out the reproductive interference caused by pollination among relative species and the strategies avoiding the interference.