Diversity among populations of switchgrass based on RAPD markers

Information on the amount of genetic diversity in switchgrass (Panicum virgatum L.) is necessary to enhance the effectiveness of breeding programs and germplasm conservation efforts. This study characterized and assessed genetic diversity by means of RAPD markers among 14 populations representing upland and lowland switchgrass ecotypes. Forty-five of 128 primers produced polymorphic markers among sets of genomic DNA pooled from individual genotypes of each population. Five primers were selected to amplify a total of 91 polymorphic loci among genotypes. The RAPD markers were scored for presence or absence of bands to generate distance matrices for cluster analysis. Overall similarity was 65% among populations compared to 81% within populations. Blackwell and Caddo were the most similar populations (78%) based on RAPD markers, whereas Alamo and Forestburg were the most divergent (53%). Cluster analysis clearly segregated populations into two main groups (putatively based on ecotype) and united individual genotypes within a population into discrete groups within the larger clusters. Although the relationship between ploidy level and ecotype remained unclear, RAPD profiles can be used to identify switchgrass populations and may be useful in predicting relationships between experimental germplasm sources and released populations.