Evaluation of Genetic Diversity of Proso Millet Germplasm Available in the United States using Simple-Sequence Repeat Markers

Proso millet (Panicum miliaceum L.) is the best rotational crop in most dryland production areas in the semiarid US High Plains because of the highest water use efficiency among all cereal crops and short growing season. In the United States, it is used for birdseed, but it is used mostly for human consumption in Asia and Europe. Genomic resources and genetic research of this crop are limited. There is no report of molecular marker-based genetic diversity analysis of the US germplasm, which is important for its genetic improvement. The objective of this study was to evaluate genetic diversity of US proso millet germplasm based on DNA markers. A set of 90 proso millet genotypes (landraces and cultivars) and 100 simple-sequence repeat (SSR) markers were used. Cluster analysis was based on unweighed pair-group method with arithmetic average (UPGMA) and principal component analysis (PCA) using NTSYSpc software. A total of 1287 alleles with size range from 40 to 1500 bp were amplified by the 100 SSR markers. The US proso millet germplasm used in this report is highly genetically diverse. The genotypes formed one major and two minor groups, which correspond to their geographic origin, pedigree, and morphoagronomic traits with few exceptions. All the cultivars developed in the United States remained together in a subcluster within Group 2. Many of these SSR markers with high resolving power were very informative and could be useful for further genetic diversity studies of proso millet. This study would have significant implications for future proso millet genetic improvement.