Genetic monitoring of introgressed alleles from Gossypium arboreum L. into G. hirsutum L. using SSR markers: a potential approach for bringing new alleles under cultivation

In the present investigation, a BC4F2 population was developed from a cross [(2 G. arboreum) G. hirsutum] for transferring resistance to cotton leaf curl disease (CLCuD) from G. arboreum into G. hirsutum. Both parent species were surveyed with 156 SSR markers, and 19 SSRs were found polymorphic amplifying 81 alleles. Out of these, 31 alleles were informative (nine derived from G. arboreum while 24 derived from G. hirsutum). Four high yielding BC4F2 selected plants were surveyed with these polymorphic SSRs. Two SSR markers (JESPR-156-closely linked with QTLs conferring resistance to CLCuD and MGHES-15-closely linked with genes involved in shaping plant architecture) showed introgression of alleles derived from G. arboreum into G. hirsutum (BC4F2). One novel allele (not derived from either of the parent species) was also amplified in one of the BC4F2 plants, possibly generated due to structural changes in cotton genome after polyploidization, or colchicine treatment/ovule culture. These genetic introgressions monitored through DNA markers from alien sources into cultivated gene pool can buffer the potential risks of diseases and the changing environment.