A New Insight Into Pollen Release and Presentation in Actinidiaceae Plants: The Case Study of Dioecious Actinidia...

Sequential pollen presentation is a reproductive strategy adopted by plants to enhance the efficiency and accuracy of pollen export and receipt, as well as to promote outcrossing. Actinidia arguta exhibits a typical characteristic of sequential pollen presentation. In this study, indoor and field observation methods were employed to conduct a tracking investigation on the anther dehiscence mode, pollen presentation strategy of male, and the floral characteristics and pollination traits of both female and male. The results showed that the dark-colored structures surrounding the ovary in the female flower are sterile staminodes. The female flowers possess multi-lobed stigmas arranged radially. The anthers of male are black, and the petals of female are significantly larger than male. The anther dehiscence mode of male A. arguta is "unzipping" longitudinal dehiscence for pollen release, and its pollen presentation strategy is sequential presentation. The peak period of pollen release effectively overlaps with the periods of pollen viability, stigma receptivity, and nectar secretion at different flowering stages. This reduces pollen waste and promotes outcrossing pollination. Male A. arguta produces a large amount of pollen and secretes more nectar than female. This attracts more pollinating insects, indicating that A. arguta is a typical insect-pollinated plant. Apis cerana and Bombus are the main pollinators, and pollination is accomplished by relying on these pollinating insects to transfer pollen from male to the stigmas of female. Exploring the pollination mechanism and characteristics of A. arguta pollen deepens the scientific understanding of its pollination process.