Diversity comparison and phylogenetic relationships of S. bicolor and S. sudanense as revealed by SSR markers

Abstract

Phylogenetic relationships among 48 accessions of sorghum ( Sorghum bicolor), sudangrass ( S. sudanense) and their relatives ( S. propinquum, S. halepense, Zea mexicana, Z. mays) were investigated using SSR markers. The 91 SSR primer pairs generated a total of 723 polymorphic alleles, with an average of 7.945 alleles per locus, and a range of 2–19 alleles. The average genetic diversity, as measured by the polymorphic information content (PIC), was 0.783. The average polymorphic rates were 84.530% and 78.483% within sorghum and sudangrass, respectively. The PIC values were 0.774 and 0.770, respectively, and there was no significant difference ( P > 0.05) between sorghum and sudangrass. Additionally, the genetic distance (GD sor–su) between sorghum and sudangrass was only 0.035, suggesting a high degree of genetic homogeneity. Genetic similarity (GS) values between all varieties ranged from 0.217 to 0.975 and were used to produce a dendrogram. The 48 accessions were clustered into five groups (GS = 0.766), specifically, group I (consisting of sorghum, sudangrass and sorghum–sudangrass hybrids), group II ( S. propinquum), group III ( S. halepense), group IV ( Z. mexicana) and group V ( Z. mays). Results of our analyses suggest the sudangrass/sorghum relationship is sufficiently close to place them both within the same species – sorghum ( S. bicolor).