Introduction of East African Diploid Cotton Genetic Variation Into Upland Cotton

The African wild diploid cotton species, Gossypium longicalyx Hutch. & Lee. (2n = 2x = 26, F1F1) presents many valuable traits that can be introduced into Gossypium hirsutum to enhance its narrow genetic basis. To assess the possibility of using monosomic alien addition line (MAAL) of G. longicalyx in G. hirsutum in an interspecific breeding program, the progeny of ten MAALs was characterized. Chromosome counting allowed to identify the addition of single alien chromosome in 9 of the 10 lines studied. The analysis of the chromosome configurations at metaphase showed the presence of multivalent associations involving the supernumerary chromosome of G. longicalyx, indicating the occurrence of recombination between the G. longicalyx and G. hirsutum chromosomes. The use of microsatellite markers provided evidence of multiple introgressions of G. longicalyx DNA in the recipient species. It appeared from the SSR analysis that only four different supernumerary alien chromosomes were present in the studied MAALs. These results confirm the low genetic distance existing between the chromosomes of G. longicalyx and those of Ah sub-genome. They highlight the opportunities and constraints associated with the use of G. longicalyx in a breeding program of upland cotton.