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

Abstract

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 charact erized 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 BC 2 F 1 generation and the stay - green Quantitative Trait Loc i (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 F 1 generation, two o f these QTL , were transferred into three genotypes. In the BC 1 F 1 generation, 32 genotypes had at least one QTL incorporated. From a population of 157 BC 2 F 1 progenies, 45 genotypes had incorporated either one or two of the stay - green QTL. Despite a few numb er 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