Assessment of genetic diversity in broomcorn millet (Panicum miliaceum L.) using SSR markers.

The genetic diversity of 118 accessions of broomcorn millet (Panicum miliaceum L.), collected from various ecological areas, was analyzed. Using 46 SSR (Simple Sequence Repeat) polymorphic markers from rice, wheat, oat and barley, a total of 226 alleles were found, which exhibited moderate level of diversity. The number of alleles per primer ranged from two to nine, with an average of 4.91. The range of polymorphism information content (PIC) was 0.284-0.980 (average, 0.793). The expected heterozygosity (He) varied from 0.346 to 0.989, with an average of 0.834. The average coefficient of the genetic similarity of SSR markers among the 118 accessions was 0.609, and it ranged from 0.461 to 0.851. The UPGMA (Unweight Pair Group Method with Arithmetic Mean) clustering analysis at the genetic similarity value of 0.609 grouped the 118 accessions into five groups. Mantel test meant that geographical origin and genetic distance presented positive correlation. The clustering results were consistent with known information on ecological growing areas. The genetic similarity coefficient of the accessions in the Loess Plateau ecotype was significantly lower than those in the other ecotypes. It indicates that the highest level of genetic diversity occurred in the Loess Plateau, which is probably the original site of Panicum miliaceum.