Sudangrass [ Sorghum sudanense (Piper) Stapf] is a hybrid between grain sorghum and its wild relative S. bicolor ssp. verticilli orum and is grown as a forage crop due to its high biomass production and low dhurrin content compared to sorghum. In this study, we sequenced the sudangrass genome and showed that the assembled genome was 715.95 Mb with 35,243 protein-coding genes. Phylogenetic analysis with whole genome proteomes demonstrated that the sudangrass genome was more similar to US commercial sorghums than to its wild relatives and cultivated sorghums from Africa. We con rmed that at seedling stage, sudangrass accessions contained signi cantly lower dhurrin as measured by hydrocyanic acid potential (HCN-p) than cultivated sorghum accessions. Genome-wide association study identi ed a QTL most tightly associated with HCN-p and the linked SNPs were located in the 3' UTR of Sobic.001G012300 which encodes CYP79A1, the enzyme that catalyzes the rst step of dhurrin biosynthesis. As in other grasses such as maize and rice, we also found that copia/gypsy long terminal repeat retrotransposons were more abundant in cultivated than in wild sorghums, implying that crop domestication in the grasses was accompanied by increased copia/gypsy LTR retrotransposon insertions in the genomes.

Sudangrass [ Sorghum sudanense (Piper) Stapf] is a hybrid between grain sorghum and its wild relative S. bicolor ssp. verticilliflorum and is grown as a forage crop due to its high biomass production and low dhurrin content compared to sorghum. In this study, we sequenced the sudangrass genome and showed that the assembled genome was 715.95 Mb with 35,243 protein-coding genes. Phylogenetic analysis with whole genome proteomes demonstrated that the sudangrass genome was more similar to US commercial sorghums than to its wild relatives and cultivated sorghums from Africa. We confirmed that at seedling stage, sudangrass accessions contained significantly lower dhurrin as measured by hydrocyanic acid potential (HCN-p) than cultivated sorghum accessions. Genome-wide association study identified a QTL most tightly associated with HCN-p and the linked SNPs were located in the 3’ UTR of Sobic.001G012300 which encodes CYP79A1, the enzyme that catalyzes the first step of dhurrin biosynthesis. As in other grasses such as maize and rice, we also found that copia/gypsy long terminal repeat retrotransposons were more abundant in cultivated than in wild sorghums, implying that crop domestication in the grasses was accompanied by increased copia/gypsy LTR retrotransposon insertions in the genomes.

Sorghum-sudanense is a hybrid of sorghum and Sudanese grass and is widely used in animal husbandry and aquaculture because of its high yield, excellent quality and wide adaptability. Using high-throughput sequencing, we constructed a high-density genetic map of sorghum Tx623A Â sudangrass S722 with 103 recombinant inbred lines (RILs) in this study and mapped quantitative trait loci (QTLs) for plant height (PH), stem diameter (SD), tiller number (TN), fresh weight (FW) and dry weight per plant (DW). The map included 1610 markers with a total length of 2329 cM and QTL mapping identified 19 QTLs, including two for PH, three for SD, four for TN, four for FW and five for DW. We detected two QTL clusters containing overlapping QTLs for PH, FW and DW. Orthologs of three SD candidate genes from maize were found within two SD QTLs. The identification of these QTLs will be useful for cloning the corresponding genes for these traits and developing marker-assisted selection (MAS) in future sorghum breeding programs.

Sorghum-sudanense is a hybrid of sorghum and Sudanese grass and is widely used in animal husbandry and aquaculture because of its high yield, excellent quality and wide adaptability. Its total fresh biomass yield, fresh biomass yield at each cut and nutritional quality are better than their parents. Using high-throughput sequencing, we constructed a high-density genetic map of sorghum Tx623A×sudangrass S722 with 103 recombinant inbred lines (RIL) in this study and mapped quantitative trait loci (QTLs) for plant height (PH), stem diameter (SD), tiller number (TN), fresh weight (FW) and dry weight per plant (DW). The map included 1,610 markers with a total length of 2,329 cM and QTL mapping identified 19 QTLs, including two for PH, three for SD, four for TN, four for FW and five for DW. We detected two QTL clusters containing overlapping QTLs for PH, FW and DW. Orthologs of three SD candidate genes from maize were found within two SD QTLs. The identification of these QTLs will be useful for dissecting important traits and developing marker-assisted selection (MAS) in future sorghum breeding programs.