QTL MAPPING OF FIVE FORAGE QUALITY TRAITS IN SORGHUM x SUDANGRASS

The quantitative trait locus (QTL) mapping for quality traits will improve the breeding of sorghum-sudangrass. In this research, we characterized the phenotype of 126 RILs and their parents -Tx623A (sorghum) and Sa(Sudangrass) for two successive years ( 2018 and 2019). The phenotypes included five forage quality traits which were crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL) and the content of hemicellulose (HC). We also mapped 19 QTLs controlling these traits in a RIL population between sorghum Tx623A and sudangrass Sa. A high density genetic map was constructed by RAD-seq. There were 1065 markers and the total length was 1191.7 cM in the genetic map. Consequently, a total of 19 QTLs were detected for the five traits, which included one QTL for CP, five QTLs for NDF, three QTLs for ADF, two QTLs for ADL and eight QTLs for HC. Four overlapping QTLs were detected for NDF, ADF, ADL and HC. The research results will supply very meaningful information to make better the forage quality breeding in sorghum-sudangrass hybrids.