Genetic Diversity and Population Structure of Broomcorn Sorghum Investigated with Simple Sequence Repeat Markers

In order to study the genetic diversity and population structure of broomcorn, a special type of sorghum for broom making, a total of 140 accessions of sorghum varieties including broomcorn (72), half-broomcorn (4), non-broomcorn (64) accessions were genotyped by using 45 simple sequence repeat (SSR) markers that are evenly distributed throughout the sorghum genome. These genotyping analyses demonstrated that the average values of NA (number of alleles per locus), PIC (polymorphism information content) and He (genetic diversity/expected heterozygosity) of the broomcorn accessions were 9.09, 0.60 and 0.63, respectively, which were higher than that of the half-broomcorn accessions (NA, 2.64; PIC, 0.46; He, 0.52) but lower than that of the non-broomcorn accessions (NA, 11.69; PIC, 0.73; He, 0.75). These results implied that the genetic diversity of broomcorn is not as abundant as that of non-broomcorn, and the genetic diversity level of broomcorn is relatively rich. Moreover, the STRUCTURE analysis, phylogenetic analysis and principle coordinate analysis (PCoA) indicated that most of broomcorn collections from Ethiopia (Africa) and Turkey (West Asia) were clustered into one group whereas a majority of broomcorn accessions from East Asia (China, South Korea) were grouped into another group. Two broomcorn individuals from Africa (Sudan) belonged to another distinctive group. These results suggest that broomcorn possesses a wide genetic background and can be divided into three types of differentiation. The information of this study is useful for the understanding of domesticating history and broomcorn differentiations.