Unique growth paths of heterospecific pollen tubes result in late entry into ovules in the gynoecium of Sagittaria (Alismataceae).
Unique growth paths of heterospecific pollen tubes result in late entry into ovules in the gynoecium of Sagittaria (Alismataceae).
复制标题
异种花粉管的独特生长路径导致慈姑（泽泻科）的雌蕊较晚进入胚珠。
作者：
N. Lyu;W. Du;X.
花粉-雌蕊相互作用是被子植物生殖生物学中的一个基本过程，在维持同域生存的早期物种中起着特别重要的作用。然而，大多数以前的研究都集中在合心皮雌蕊（心皮融合）的物种，而不是那些离心皮雌蕊（不融合心皮）。在本研究中，我们调查了慈姑属种，其中有离生果雌蕊的同种花粉管的生长相比，异种花粉管。在荧光显微镜下观察了矮针茅和三叶针茅的同种和异种花粉管生长情况。异种和同种的花粉管几乎同时到达子房内的子房室。然而，同种花粉管直接进入胚珠，而异种管穿过心皮基部和邻近的花托组织，最终使其他未受精的胚珠受精。这种较长的路线所采取的异种花粉管，因此造成延迟所需的时间进入胚珠。此外，异种花粉管在授粉早期和高峰期表现出相似的生长模式。异种花粉管在授粉后期的生长规律与同种花粉管在授粉高峰期的生长规律相似。异种和同种的花粉管受精途径不同。异种花粉进入胚珠的延迟可能是离果植物产生同种花粉优势的一种新机制。
Pollen-pistil interactions are a fundamental process in the reproductive biology of angiosperms and play a particularly important role in maintaining incipient species that exist in sympatry. However, the majority of previous studies have focused on species with syncarpous gynoecia (fused carpels) and not those with apocarpous gynoecia (unfused carpels). In the present study, we investigated the growth of conspecific pollen tubes compared to heterospecific pollen tubes in Sagittaria species, which have apocarpous gynoecia. We conducted controlled pollinations between S. pygmaea and S. trifolia and observed the growth of conspecific and heterospecific pollen tubes under a fluorescence microscope. Heterospecific and conspecific pollen tubes arrived at locules within the ovaries near simultaneously. 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. This longer route taken by heterospecific pollen tubes therefore caused a delay in the time required to enter into the ovules. Furthermore, heterospecific pollen tubes displayed similar growth patterns at early and peak pollination. The growth pattern of heterospecific pollen tubes at late pollination was similar to that of conspecific pollen tubes at peak pollination. Heterospecific and conspecific pollen tubes took different routes to fertilize ovules. A delayed entry of heterospecific pollen into ovules may be a novel mechanism of conspecific pollen advantage (CPA) for apocarpous species.