Transfering drought tolerance of the stay-green trait in sorghum from E36-1 an Ethiopian line into Ochuti, a farmer preferred Kenyan variety
In this study marker-assisted backcross breeding was utilized to transfer stay-green QTL from the Ethiopian donor parental line E36-1 into a Kenyan Farmer-preferred variety, Ochuti as the recurrent parental line. E36-1 has 3 stay green QTL located at three linkage groups of sorghum genome (SBI-OI, SBI-07 and SBI-IO). Five foreground markers that were polymorphic between the two parental genotypes were used to identify true F I individuals. Only two of the possible three QTL namely, SBI-07 and SBI-IO were identified as having been transferred into three individual genotypes. This is because there were no polymorphic markers available flanking stay-green QTL at linkage group SBI-01. The identified FI genotypes were used as the female parents in the generation of 128 BCIFI individuals. About 25% of the BCIFI progenies that were genotyped had at least one QTL introgressed. As is the case in all marker-assisted back-cross breeding, the rate of success in introgressing QTL from donor to recurrent parental lines, depends on the number of plants screened. Thirty polymorphic background SSR markers were used to select twenty BCIF I individuals that had a higher proportion of recurrent parent genome. These were backcrossed to recurrent parent to generate 157 BC2FI family lines. These were screened with the five foreground SSR markers where 45 individuals were confirmed to be having among them single and double introgressions of stay-green QTL. The results of this study showed that, it is possible to introgress stay-green QTL that govern drought tolerance in from an exotic source to a locally preferred variety in sorghum successfully.