Pollination biology of Gossypium turneri: Autonomous selfing provides reproductive assurance in an endangered wild cotton from Sonora, Mexico

The wild cotton, Gossypium turneri, is a rare and endemic species from the state of Sonora, Mexico, threatened by habitat destruction, tourism development, and buffelgrass invasion in the municipality of Guaymas. As a consequence, G. turneri is now classified as endangered under Mexican legislation. This study aimed to document several aspects of the reproductive biology of this wild cotton to suggest conservation plans. The flowers of G. turneri remain open for only 1 day. Throughout the day, the flowers are visited by a diverse group of insects, including bees and butterflies. Pollination treatments revealed that this species is self-compatible, capable of autonomous self-pollination, and showed mixed evidence of pollen limitation. Although the flowers exhibit herkogamy, curved styles were observed that make the stigma come into contact with anthers. These results indicate that autonomous self-pollination is caused by style curvature. Fruit set values and seed production per fruit in open pollinated control flowers were low, suggesting that this species produces a small number of seeds. These results provide new insights into this rare species, indicating that the species has a mechanism that provides reproductive assurance under low pollinator visitation, allowing for its persistence. The collection of seeds from the remaining populations for germplasm banks and the maintenance of live plants in botanical gardens are proposed for the conservation of this rare species.