生态学报2017，Vol.37Issue(24)：8467-8476,10.DOI:10.5846/stxb201611212365
雄全异株流苏树的花部特征及繁育系统研究
Floral syndrome and reproductive strategy of an androdioecious species, Chionanthus retusus (Oleaceae)
摘要
Abstract
Androdioecy is a rare reproductive strategy in plants.Comprehensive studies on the flowering dynamics,pollinators,morphology,and structure of flowers,breeding systems,and controlled pollination were performed in four populations of the Chinese fringe tree,Chionanthus retusus.This species is typically androdioecious in morphology,with male and hermaphroditic individuals coexisting in the same population.Results showed that the development of the stamens of male and hermaphrodite flowers was similar,and could produce functional 2-cell pollen grains.Two carpel primordia appeared inside the stamens of males and hermaphrodites at the initial pistil stage.Subsequently,these two carpels fused with each other and differentiated into the ovary and stigma in hermaphroditic flowers.However,in males,a cavity was formed after the fusion of two carpels,and it stopped growing further and eventually degenerated.This species was protogynous,and the stigma was receptive throughout anthesis.Pollen grains were viable after anther dehiscence and the viability was maintained at ＞ 10％ for about 2 weeks at room temperature of 20-25℃.C.retusus is a wind-and insect-pollinated species,and the main pollinating insects belonged to Thripidae and Syrphidae.The results of controlled experiments 30 days after pollination showed that C.retusus could bear fruit under natural conditions with fruit set percentage of 34.36％.The hermaphroditic flowers were self-compatible,and the fruit set percentage under autogamy was very low,i.e.,only 10.70％.No apomixis was observed.In artificial pollination,the fruit set percentage with cross-pollination (xenogamy with pollen from male or hermaphroditic flower) was significantly higher than that with self-pollination (geitonogamy) (P ＜ 0.05).Sexual reproduction of this species was limited by the pollinators.It was demonstrated that C.retusus presented a mixed mating system,because it can produce fruit under any type of pollination tested.In terms of functional gamete production from both males and hermaphrodites,C.retusus represents a novel case of functional androdioecy in the family Oleaceae.The maintenance mechanism of androdioecy of this species could be as follows:males increase the quantity and quality of pollen,which can avoid inbreeding depression,and the self-compatibility of hermaphrodites might ensure reproductive success.Based on the presence of pistillodes in male flowers,and the results of previous studies,androdioecy might be a transition from hermaphroditism to dioecy in Oleaceae.关键词
流苏树/雄全异株/开花动态/传粉机制Key words
Chionanthus retusus/androdioecy/flowering dynamics/pollination mechanisms引用本文复制引用
何艳霞,孔令茜,陈鹏臻,苗欣,尚富德..雄全异株流苏树的花部特征及繁育系统研究[J].生态学报,2017,37(24):8467-8476,10.基金项目
国家自然科学基金项目(31500572,31270738) （31500572,31270738）
