Pollination plan B: the floral phenology and mechanism of delayed selfing in jaltomata repandidentata (solanaceae)

Jaltomata repandidentata, similar to other members of its genus, is known to be self-compatible. The following study identifies J. repandidentata as a species capable of delayed self-pollination and describes the mechanism of delayed selfing through changes in floral morphology during anthesis. This work was accomplished through monitoring changes in flower phenology and quantifying delayed selfing success through a series of pollination experiments. On the first day of flowering, flowers are pistillate and anthers remain undehisced. The stigmatic surface is functionally receptive throughout anthesis, indicating that J. repandidentata is able to import pollen during its pistillate phase. Elongation of stamen filaments and the pistil occur over a two-day flowering period. Flowers become hermaphroditic on the second day, and anthers on long filaments dehisce earlier than anthers on short filaments at this time. Prior to corolla abscission, anthers collapse onto the stigma, and self-pollination is achieved. Therefore, temporary herkagomy and dichogamy are demonstrated in the species, which prevents premature self-pollination while promoting outcrossing prior to selfing. No significant difference was found between the lengths of short stamens and pistils, and this proximity allows for self pollination by short stamens rather than long stamens, whose pollen is more likely to be exported than used in self-pollination. Delayed selfing may be further promoted through diurnal changes in flower opening size during anthesis, extensive filament bending that occurs during the final hours of flowering, and pollinator visitation. A high success of self pollination was demonstrated in bagged flowers of various accessions of J. repandidentata, and a significant difference in self-pollination success was seen when compared to Jaltomata procumbens, another species with similar floral phenology. Evidence indicates that J. procumbens as well as other Jaltomata species are also likely to carry out delayed selfing. Ecological and evolutionary ramifications of delayed selfing in J. repandidentata are discussed, as well as recommendations for further research.