Genetic mapping of Sorghum bicolor (L.) Moench QTLs that control variation in tillering and other morphological characters

Grain yield of Sorghum bicolor (L.) Moench is significantly influenced by genetically controlled variation in the number of tillers, plant height, time of anthesis, and various other morphological and physiological characters. In this study, a minimum of 27 unique QTLs that control variation in nine morphological traits, including the presence versus the absence and the height of basal tillers, were mapped, and the percentage of additive genetic variance explained by the QTLs was determined in a population of 137 recombinant inbred lines in two environments. Four QTLs explained from 86.3% to 48.9% (depending upon the environment) of the additive genetic variance in the number of basal tillers with heads, and seven QTLs explained from 85.9% to 47.9% of the additive genetic variance in panicle width. It is unlikely that different alleles were segregating in the mapping population at any of the major dwarfing loci, but five QTLs that explained from 65.8% to 52.0% of the additive genetic variance in main-culm height were mapped. QTLs controlling variation in height of the tallest basal tiller, number of basal tillers per basal-tillered plant, panicle length, leaf angle, maturity, and awn length also were mapped. Three or more QTLs were mapped in linkage groups A, E, G, and I, while none were mapped in linkage groups B and D. Several of the QTLs mapped in this study are likely candidates for marker-assisted selection in breeding programs.