Fine mapping of the fg gene using the interspecific cross of Gossypium hirsutumGossypium barbadense

Frego (fg) bract is an important agronomic trait in tetraploid cotton, which has been widely introduced into several cotton varities or lines in the past several years. In order to help us further understand the underlying molecular mechanism of frego bract development, a map-base cloning strategy was used to localize the fg locus. An F sub(2) population which comprised of 290fg individuals derived from a cross of the multiple-marker line T582 (G. hirsutum, carrying the fg gene) with Hai7124 (G. barbadense) was constructed. Genetic linkage analysis was carried out to map of the fg locus with SSR and EST-SSR markers in tetraploid cotton. Genetic linkage analysis showed that the fg locus was flanked by the marker NAU3016 and NAU3172 on the long arm of chromosome 3, with the genetic distance of 0.3cM and 4.7cM, respectively. The information of fg locus provided the basic information for the final isolation of this important gene in tetraploid cotton, these marker information could be used in marker-assisted selection in cotton.