QTLs for Energy-related Traits in a Sweet x Grain Sorghum [Sorghum bicolor (L.) Moench] Mapping Population

To meet anticipated markets for sweet sorghum [Sorghum bicolor (L.) Moench] production, the development of sweet sorghum hybrids is underway. As this development is in its infancy, genetic markers will be very useful to define the genetic basis of sugar yield components and reduce the time required to deliver new hybrids to market. The purpose of this research was to characterize genetic components that influence sweet sorghum productivity and agronomics. A grain x sweet sorghum mapping population was evaluated for 16 phenotypic traits across four environments. A population of 185 F-3-derived F-4 (F-3:4) lines was derived from the parents 'BTx3197' and 'Rio', which are dry-stalked grain and juicy-stalked sweet sorghums, respectively. A genetic map was constructed with 381 single nucleotide polymorphisms, and quantitative trait locus (QTL) analysis was performed. A major and previously reported QTL for soluble solids was identified on chromosome 3, but in contrast to previous studies, this QTL colocalized with other QTLs that had negative influences on desirable traits. Therefore, selection for this QTL may not be advantageous. A limited number of QTLs for percent moisture were found, and results indicated that the dry-stalk phenotype does not affect moisture content as measured in this study. Thus, breeding for moisture content will be more challenging than previously expected. The absence of dominance effects for the brix trait indicated that brix must be high in both parents to produce high brix in hybrids.