经典观点认为心皮从离生向合生演化是被子植物的一个重要变革，但系统发育分析表明约1/4的离生心皮来自"逆向转变"。离生心皮类是否一定在花部资源配置及子代产量与质量方面处于劣势？雌蕊外花粉管生长（EGPG）的发现对传统观念是一个极大冲击：EGPG使离生心皮在功能上类似于合生心皮，导致雌蕊群中未受粉雌蕊结实，并可能使花粉竞争从单个雌蕊扩展到整个雌蕊群。最近的研究发现，EGPG在离生心皮类群中较为普遍，且可被分为3种类型：supra-/infra-/extra-stylar EGPG。问题在于：1）EGPG与雌蕊群结构有何关系？2）离生心皮类植物有性生殖是否存在花粉限制？不同类型的EGPG对子代数量和质量有何影响？3）EGPG何以无序分布于系统树的不同分支上？合生心皮向离生心皮逆转是否与EGPG带来的利益有关？本项目将探讨被子植物心皮演化对花粉管生长途径的适应以及花粉管雌蕊外生长对生殖保障的意义。

Transition from apocarpy to syncarpy in angiosperms is thought traditionally to be a great evolution event, however, there are approximately one quarter of the apocarpy occurring from reversals based on phylogenetic analysis. Do apocarpous plants have disadvantages in floral resource allocation as well as offspring quantity and quality in comparision to the syncarpous group? The finding of extra-gynoecial pollen-tube growth (EGPG) may be a considerable impact to the traditional concept about the disadvantages of apocarpy. The apocarpous gynoecia are functionally similar to the syncarpous gynoecia due to the present of EGPG, which may fertilize the unpollinated carpels in the same gynoecium and could make the pollen tube competition from a single carpel expanding to the whole gynoecium. Based on our recent study, EGPG is phylogenetically widespread in apocarpous angiosperms, and they can be classified into three types: supra-/infra-/extra-stylar EGPG. Here, we want to know: 1) What is the relationship between EGPG and gynoecial structure? 2) Does pollen limitation do occure in apocarpous species? And what are the impacts of different types of EGPG on offspring quantity and quality in apocarpous species? 3) Why does EGPG distribute unsystematically on the phylogenetic tree? Do the gynoecial structure reversals from syncarpy to apocarpy have some relationships with the advantages by EGPG? In this project, we will focus on the adaptation of the evolution of gynoecial structures to the different pathway of pollen tube growth, as well as the reproductive assurance by extra-gynoecial pollen-tube growths in apocarpous angiosperms.