Abstract

Bermudagrass (Cynodon spp.) is widely used on golf courses and sport fields in Florida. Most cultivars used on golf courses are triploid bermudagrass (Cynodon dactylon [L.] Pers. var. dactylon × C. transvaalensis Burtt-Davy) resulting from hybridizations between tetraploid common bermudagrass and diploid African bermudagrass. In order to breed and develop bermudagrass cultivars with superior characteristics, it is essential to know the ploidy levels of available bermudagrass accessions and select fertile ones. The objective of this study was to determine the DNA content and ploidy level of bermudagrass germplasm accessions in the University of Florida germplasm collection to aid in future cultivar breeding. Flow cytometry was used to determine the nuclear DNA contents of 48 bermudagrass accessions, and one diploid (2%), 19 triploid (40%), 24 tetraploid (50%), one pentaploid (2%) and three hexaploid (6%) accessions were identified. The range of the nuclear DNA contents was 1.17, 1.38 to 1.61, 1.94 to 2.24, 2.47 and 2.64 to 2.75 pg/2C nucleus^-1 for the respective ploidy levels. As such, tetraploid and hexaploid accessions could be utilized for future breeding efforts. The triploid accessions could be the results of mutations that have occurred in existing commercial bermudagrass cultivars or from natural hybrids between diploid C. transvaalensis and tetraploid C. dactylon.

Key words: Cynodon spp., flow cytometry, nuclear DNA content, ploidy level.