Protogyny and delayed autonomous self‐pollination in the desert herb Zygophyllum macropterum (Zygophyllaceae)

Abstract

Protogyny and delayed selfing are two mechanisms in facilitating outcrossing and increasing female and male function in self-compatible plant species. However, both mechanisms are rarely reported within a species. Here, we investigated pistil and stamen development, breeding system, and pollination biology of the desert herb Zygophyllum macropterum C. A. Mey. by use of field observations and manipulation experiments. Our primary aim was to assess whether protogyny and delayed autonomous self-pollination occurred in this species. Zygophyllum macropterum is a spring flowering species with a floral longevity of approximately 3 days, including the female stage and the bisexual stage. Movement herkogamy occurred during both stages. The stigma was receptive when it was exposed from the corolla. The time of first anther dehiscence was approximately 12 h after stigma exposure. These results indicated that Z. macropterum is protogynous. Different pollination treatments showed that this species is selfcompatible and can self-pollinate autonomously. Time of first dehiscence of anther overtopping the stigma was approximately 16 h after stigma exposure, suggesting that autonomous self-pollination can occur in middle-late anthesis, and thus can be defined as delayed autonomous self-pollination. Anthophora plumipes Pallas. was the only pollinator of Z. macropterum. The unfavorable spring desert environment and the small corolla mouth diameter at the female stage would limit pollinator activity and thus lead to failure of outcrossing and occurrence of delayed selfpollination. Therefore, both protogyny and delayed selfing play an important role in enhancing the opportunity for outcrossing and reproductive assurance of Z. macropterum in the spring desert environment.

The best of both worlds? A review of delayed selfing in flowering plants

“…Mechanical and developmental processes often work together to optimize both outcrossing and delayed selfing. For example, in the protogynous desert herb Zygophyllum macropterum, herkogamy present during the phase of stigma receptivity prevents physical interference by stamens; but as anthers dehisce at the end of the female phase, filaments elongate to reduce stigmaanther distance, and self-pollination occurs (Mamut et al, 2014). Incomplete protogyny, alone or combined with other mechanisms, was reported to promote delayed selfing in 19 of 55 genera (Fig.…”

Protection against insect predation during fruit development: the role of fleshy fruit wings of three species of Zygophyllum in the cold desert of Central Asia

“…Zygophyllum potaninii and Z. macropterum are reported to be perennial spring-flowering species, while Z. lehmannianum is an annual ( Liu and Zhou, 1998 ; Mamut et al., 2014 ). They are widely distributed in the Junggar Desert and play a pivotal role in maintaining the stability of the desert ecosystem by increasing the surface roughness of the soil.…”

Floral Biology and Pollination of Red Hot F1 Hybrid Hot Pepper (Capsicum frutescens x C. annuum) in the Philippines

“…In the absence of animal pollinators, flowers of hot pepper can be jostled by strong winds and the pendant flower orientation might increase the chances of pollen landing to selfstigmas, effecting self-pollination. In this case, seed production is favored more than outcross begetting reproductive success (Karron and Mitchell 2012;Mamut et al 2014).…”