| dc.description.abstract | The tetraploid cultivated cotton Gossypium hirsutum (2n=4x=52) normally will not form viable F₁ hybrids with G. davidsonii or any tetraploid homozygous for Le₂ᵈᵃᵛ. Many or most G. hirsutum plants are homozygous for alleles Le₁ and Le₂; hybrids bearing an Le₂ᵈᵃᵛ allele, and either or both Le₁ or Le₂, undergo a physiological reaction leading to seedling inviability. In contrast, Le₂ᵈᵃᵛ is fully compatible with alleles le₁ and le₂; i.e. le₁le₁le₂Le₂ᵈᵃᵛ plants are fully viable. Prior to this study, two facts suggested some G. hirsutum types may harbor le₁ and/or le₂ alleles. First, only a few lines had been tested. Second, homozygosity for le₁ or le₂ could be masked by homozygosity for Le₁ or Le₂ respectively, since the inviability reaction is epistatic over the compatability response. Successful deployment of new breeding procedures being developed for mass extraction of doubled haploids from G. hirsutum is contingent on the absence of the alleles le₁ and le₂. The purpose of the study was to determine the frequency of the alleles le₁ and le₂ in a representative sample of U.S. G. hirsutum germplasm, consisting of sixty-three varieties. | en |
