Mapping quantitative trait loci for five forage quality traits in a sorghum-sudangrass hybrid

The identification of quantitative trait loci (QTLs) affecting forage quality traits enables an understanding of the genetic mechanism of these loci. The aim of the present study was to detect QTLs for the whole-plant protein content (WP), whole-plant fat content (WF), neutral detergent fiber (NDF), acid detergent fiber (ADF), and whole-plant ash content (WA) using a population of 184 F-2 individuals from a cross between sorghum Tx623A and sudangrass Sa. Correlation analysis was performed between the five forage quality traits. WP was found to be positively correlated with WF, NDF, and ADF. Furthermore, NDF was positively correlated with ADF but negatively correlated with WA. A genetic map with 124 SSR markers was constructed for QTL mapping. A total of 12 QTLs associated with the five forage quality traits were detected. Of these QTLs, qNDF3, qNDF8, and qADF8 explained more than 10% of the phenotypic variation. Additionally, although all of the QTLs exhibited additive and dominant effects, they mainly exhibited dominant effects. Our results provide important information for marker-assisted selection breeding of sorghum-sudangrass hybrids.