Directional Breeding Generates Distinct Genetic Diversity in Hybrid Turf Bermudagrass as Probed with SSR Markers

Abstract

Bermudagrass (Cynodon spp.) is one of the drought-resistant warm-season turfgrasses adapted to the southern and transitional zones in the United States. Multiple hybrid varieties have been developed and released for use as a turfgrass and others are in pipeline. Increasing genetic di-versity of commercial varieties is vital to tackle stress tolerance. A DNA profiling study of 21 experimental selections from the Oklahoma State University (OSU) turfgrass breeding program and 11 cultivars was conducted using 51 simple sequence repeat (SSR) primer pairs that spread across the bermudagrass genome. Pairwise genetic relationship analysis among the genotypes using 352 polymorphic bands showed genetic similarity coefficients ranging from 0.59 to 0.89. Cluster analysis using the un-weighted paired group method with arithmetic average (UPGMA) method grouped the entries into six clusters. Correlation analysis identified different levels of pairwise genetic relationship among the entries that largely reflected parental relationship. Di-rectional breeding and selection for cold hardiness or drought resistance created progeny that had distinct genetic diversity in the tested bermudagrasses. It is evident that an increase in genetic diversity of the existing cultivar pool with the release of one or more of the experimental selec-tions for commercial use will strengthen and improve bermudagrass systems.