Cytogenetic Study on Trispecific Hybrid from Gossypium hirsutum L., G. australe and G. capitis-viridis

Abstract

There are rich germplasm resources in Gossypium and wild cotton species possess many valuable agronomic traits which cultivated cotton always lacks. In order to introgress the useful traits from wild species G. australe and G. capitis-viridis into cultivated species for improving upland cotton, tetraploid G. hirsutum was crossed directly with C-genome species G. australe as the pollen-providing parent, creating a triploid hybrid. Chromosome doubling of this triploid hybrid leads to an allohexaploid which was then crossed with B-genome wild species G. capitis-viridis, resulting in trispecific hybrid (G. hirsutum, G. australe and G. capitis-viridis). The characteristic of chromosome behavior during meiosis of trispecific hybrid F 1 was further investigated in this study. Results indicated that the meiosis of trispecific hybrid was abnormal, which mainly reflected that the chromosomes were divided unequally during the anaphase II; and many abnormal multispores appeared in the telophase II, which finally developed into abortive pollen grains, directly leading to the sterility of trispecific hybrid F 1. This study provides the main reason of sterility for this hybrid and supplies the theory basis and the effective method for restoring the fertility and further creating new cotton intermediate germplasms.