A major QTL for plant height is linked with bloom locus in sorghum [Sorghum bicolor (L.) Moench]

Plant height is one of the most important agronomic traits in sorghum with its relevance for biomass, grain yield, fodder and lodging. To understand its genetic basis, the quantitative trait loci (QTL) were identified using a recombinant inbred line (RIL) population consisting of 168 RILs derived from the cross between the two sorghum inbred lines 296B (dwarf) and IS18551 (tall) over six seasons. Two major QTL were identified one each on chromosomes SBI-06 and SBI-07 corresponding to the Dw2 and Dw3 gene loci together accounting 41 % plant height variation. In addition, a morphological bloom trait locus which remained unlinked in the linkage map was found to be significantly linked with plant height in single marker analysis explaining 22 % of the trait variation. By comparing the map positions of Dw1, Dw2 and Dw3, the new locus for plant height linked with bloom is proposed as Dw4 locus. Both SSR and the morphological bloom loci linked with height QTL of the present study can be employed as effective tools in marker-assisted breeding for rapid conversion of selected inbred parent lines either as dwarf seed (male sterile) parents or taller pollinators for hybrid seed industry, or for developing high biomass lines in sweet sorghum for exploitation as high bio-fuel crop.