Cytology and pollen grain fertility in creeping bentgrass interspecific and intergeneric hybrids

Creeping bentgrass (Agrostis stolonifera L. or A. palustris Huds.) is a highly outcrossing allotetraploid species. It can form hybrids with a number of other Agrostis species and Polypogon genus. However, cytology and pollen grain fertility of the creeping bentgrass interspecific and intergeneric hybrids are not well known. In this research, chromosome pairing behaviors during meiosis I in F₁ and pollen viability of F₁ hybrids, as well as seed set rate and seed germination rate of backcrosses were studied in hybrids between creeping bentgrass, and other bentgrass species and three species of Polypogon genus. Abnormal chromosome pairing, laggard chromosomes, and premature segregation in F₁ hybrids were found. Pollen viability ranged from 1.6 to 48.5% amongst F₁ hybrids, significantly lower than that of the parents (85.5–94.1%). Some hybrids produced pollens of different sizes within the same anther. Seed set following backcrosses using F₁ hybrids as the male parent and creeping bentgrass as the recurrent parent was significantly lower than their parents. The study of chromosome paring behaviors and progeny fecundity are important in utilizing the alien genes to improve bio-stress and abio-stress resistance, and in assessing the potential transgene risks of creeping bentgrass.