Abstract Detail

Reproductive Processes

Wang, Lingyan [1], Wang, Hanxi Hanxi [1], Sheng, Lianxi [1], Chang, Shu-Mei [2].

A New Mechanism of Delayed Self-Pollination that Provides Reproductive Assurance.

Delayed self-pollination has long been recognized as an effective strategy for reproductive assurance across flowering plants. However, the mechanism by which delayed self-pollination is accomplished varies from species to species. Here we report on a newly discovered mechanism in Iris laevigata that involves a "twisting" movement of the corolla that brings anthers and stigma to contact. This twisting movement occurs as flowers senesce, which starts on average about 3 days after the onset of anthesis. We tested the effect of this corolla twisting as a delayed-selfing mechanism by applying different treatments to 30 I. laevigata flowers, including bagged intact flowers, bagged and falls-removed flowers, and open pollination. We measured seed production as well as pollen viability, stigma receptivity, petal length, and the distance between anthers and stigma in all treatments. Fruitset in the open pollination treatment reached about 64.3% ± 5.64% fruitset in sunny days, but it dropped to 38.8% ± 0.05% in rainy days which was frequent during the flowering season of I. laevigata. Our results show that despite the flowers being protandrous, pollen remained viable in late anthesis, enabling successful delayed self-pollination. In the pollinator exclusion treatments, we found that the corolla twisting alone led to about 11% of flowers setting fruits, contrasting to the 0% fruitset when we removed the falls (large petaloid sepals) of the flowers. The movement of falls during senescence appears to be the main force facilitating corola twisting. Compared to open pollination, delayed selfing also resulted in lower seed number and individual seed mass. We hypothesize that delayed selfing in I. laevigata may confer reproductive assurance benefit for flowers that experience pollinator scarcity and/or precipitation, which are two common conditions in our study area. We discuss our results on the significance of delayed selfing in this species in the context of future climate change.

1 - Northeast Normal University, School of Environment, 2555 Jingyue Street, Changchun, Jilin, 130117, China
2 - University of Georgia, Department of Plant Biology, 3612 Miller Plant Sciences building, Athens, GA, 30602, USA

Keywords:
"twisting" movement of the corolla
delayed self-pollination
reproductive assurance
adaptive evolution
Iris laevigata
climate change.

Presentation Type: Oral Paper
Session: REP1, Reproductive Processes 1
Location: San Luis 2/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 10:15 AM
Number: REP1009
Abstract ID:379
Candidate for Awards:None