Improving Drought Tolerance in Sorghum bicolor L. Moench: Marker-Assisted Transfer of the Stay-Green Quantitative Trait Loci (QTL) from a Characterized Donor Source into a Local Farmer Variety

Drought stress is a major constraint to sorghum production in Kenya, especially during flowering stage. This study aimed at developing drought tolerant sorghum varieties by transferring the stay green trait that confers drought tolerance in sorghum from a mapped and characterized donor source into an adapted farmer preferred variety. The drought tolerance donor source, E36-1 originally from Ethiopia was backcrossed into a Kenyan farmer-preferred variety, Ochuti until BC2F1 generation and the stay-green Quantitative Trait Loci (QTL) were transferred through Marker Assisted Breeding (MAB) strategy. Five polymorphic Simple Sequence Repeat (SSR) markers were used to select the 3 stay green QTL of E36-1 found in SBI-01, SBI- 07 and SBI-10 linkage groups. In the F1 generation, two of these QTL, were transferred into three genotypes. In the BC1F1 generation, 32 genotypes had at least one QTL incorporated. From a population of 157 BC2F1 progenies, 45 genotypes had incorporated either one or two of the stay-green QTL. Despite a few number of genotypes obtained through the backcrosses, the results showed that stay-green QTL and consequently drought tolerance can be transferred successfully into farmer preferred sorghum varieties through MAB.