Mapping of genomic regions associated with dwarfing and the determinate growth habit in horsegram (Macrotyloma uniflorum)

Horsegram (Macrotyloma uniflorum) - an important, self-pollinated food legume, however due to limited genomic and genetic resources the genetic improvement could not be achieved as compare to other major legumes. Our work aims at finding novel microsatellite markers and their use for the construction of a linkage map from 157 individuals of F9 recombinant inbred lines (RILs) of horsegram. The determinate growth habit and plant height are important traits for its suitability for different cropping systems. The genotypic data were generated by screening 2 395 molecular markers, of which 600 (25.05 %) polymorphic markers were selected. Two-hundred eighty-seven (287) markers were mapped on ten linkage groups (LGs) at a log of odds (LOD) of 3.5 straddling 796.76 cM with 2.78 cM of marker density. For the identification of the quantitative trait loci (QTLs), the phenotypic data recorded on the RILs for the plant height and growth habit were analysed using the statistical tools JoinMap®and Windows QTL cartographer, based on the composite interval mapping (CIM) technique. Across the ten linkage groups, we detected four QTLs (LOD ≥ 2.5) for four traits. All the traits were major QTLs as indicated by the percentage of phenotypic variance (PVE) (≥ 10%) that ranged from 13.5% to 40.3%, therefore, this is very important information which can be used in marker-assisted selection (MAS). The present genomic information generated in this orphan crop, thus, provides the base for genetic improvements by devising molecular breeding strategies.