Autonomous self-pollination in the South African orchid Satyrium rupestre Schltr.

作者：Van der Niet T^*

来源：South African Journal of Botany, 2018, 117: 215-221.

DOI：10.1016/j.sajb.2018.05.023

• Auto-pollination
• Cape floristic region
• Floral traits
• Herbarium specimens
• Pollinarium
• Rostellum

Autonomous self-pollination is widespread in orchids, but has not yet been reported for Satyrium, a genus in which floral variation is generally associated with attraction of and specialized pollination by a wide range of animals. Here I add evidence for autonomous self-pollination in the diminutive flowers of S. rupestre from the Cape Floristic Region. In recently opened flowers, pollinia of S. rupestre flowers have moved out of the anther sacs and, accompanied by reconfiguration of the caudicles, moved upwards to contact and rest on the stigma. Movement of the pollinia is associated with a narrowed central region of the rostellum, which results from tissue disintegration in flower buds; a process which does not occur in the animal-pollinated sister species S. ligulatum. Evidence of autonomous self-pollination in S. rupestre was observed both in fresh flowers in situ in two populations and in several herbarium specimens collected across the c. 400 km long species range, consistent with autonomous self-pollination as a species-wide trait. Tetrazolium staining tests indicated that more than 50% of seeds produced following self-pollination are viable. Although small amounts of liquid were detected in the spurs of S. rupestre flowers, scent emission rates and the number of massulae per pollinium are consistent with reduced reliance on animal pollinators. Future studies should focus on the extent to which the species relies on autonomous self-pollination for reproduction, to reveal whether it may serve as a mechanism of reproductive assurance in the pollinator-depauperate forest and cliff habitats of S. rupestre.

• 出版日期2018-7