连翘花柱二型的繁育系统特征研究

花柱二型是植物雌雄蕊交互异位的一种花多态现象。该研究以花柱二型植物连翘(Forsythia suspensa)为材料,通过检测其交配系统特征,比较两花型的胚珠产量、花粉质量及活力特性,以探讨花柱二型连翘两花型的功能性别分化及其进化意义。结果表明:连翘自交和型内异交坐果率均极低(<12.12%),主要以型间交配为主。长柱型个体的单花胚珠数量为(26.86±0.37)个,显著高于短柱型花,单花花粉干重为(0.47±0.02)mg,显著低于短柱型的(0.60±0.02)mg;短柱型连翘的花药含水量为(75.97±0.82)%,显著高于长柱型的(73.18±0.61)%。长柱型个体的花粉活力总体高于短柱型,其花粉寿命也更长。研究表明,连翘两花型的雌雄性繁殖投入存在显著分异,长柱型个体更易于接受花粉,通过种子实现其适合度,表现出偏雌的功能性别;短柱型个体更易于通过花粉实现其适合度,表现为偏雄的功能性别。

Study on Characteristics of Breeding System in Distylous Forsythia suspensa

Distyly is a floral polymorphism, characterized by a reciprocal positioning between stigmas and anthers in different individuals. In this study, we employed Forsythia suspensa to explore divergence in functional gender of two floral morphs and evolutionary significance of the distyly, by determining characteristics of mating system and comparing ovule number, pollen dry weight, pollen viability and longevity between two sexual morphs. The results showed that the species has heteromorphic incompatibility system, with the extremely low fruit set by selfing and intramorph pollination. The ovule number was (26.86 ± 0.37) in the long styled morph, significantly higher than that in the short styled morph. The dry weight of pollen per flower was (0.47 ± 0.02) mg in long styled morph, significantly lower than (0.60 ± 0.02) mg of the short styled one. The content of water in anther was significantly different between two morphs, which in short styled was significantly higher than in long styled. Overall, pollen viability of the short styled form was significantly lower than that in the long styled, so did pollen longevity. In conclusion, it was indicated that the relatively reproductive input in two sexual functions differed between two morphs. The long styled was female biased, realizing its fitness to larger extent by ovules, whereas the short styled was male biased, realizing the fitness largely by exporting pollen.