陆地棉、澳洲棉和绿顶棉三元杂种的细胞遗传学研究

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

摘要: 棉属有丰富的种质资源，野生棉具有栽培种所缺乏的许多优良性状，为了将野生澳洲棉和绿顶棉的优良性状导入陆地棉，以期改良栽培种陆地棉。本研究通过陆地棉和C组野生澳洲棉远缘杂交获得杂种F₁，并对其进行染色体加倍，将加倍成的异源六倍体与B组野生绿顶棉杂交，产生陆地棉、澳洲棉、绿顶棉的三元杂种，并对该三元杂种花粉母细胞减数分裂行为进行观察。结果表明：三元杂种减数分裂异常，主要表现在：后期染色体不均等分离，使得末期形成大量的不正常多分孢子，其中以五分体居多，这些多分孢子进一步发育为大量败育花粉粒，导致该杂种高度不育。本研究不仅为该三元杂种不育提供了直接原因，也为进一步探讨有效的育性恢复方法及棉花新种质的创制提供了理论依据和中间材料。

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 F₁ 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 F₁. 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.