DNA Polymorphisms at Bermudagrass Microsatellite Loci and Their Use in Genotype Fingerprinting

The turf-type bermudagrasses include dip- loid Cynodon transvaalensis Burtt Davy, tetra- ploid C. dactylon (L.) Pers., and sterile triploid hybrids produced by crosses of these species. The objective of this study was to develop a set of microsatellite markers that could distin- guish among commercially important turf-type cultivars. A genomic library enriched for the (CA/GT) n repeat motif was constructed from DNA of the 'Tifway' hybrid and sequenced to identify microsatellite regions. Twenty-fi ve mic- rosatellite-fl anking primer sets were developed and used to genotype two plant introductions and 12 turf-type cultivars. These primer sets produced an average of 10 amplicons across the 14 DNA templates. Sequences of selected amplicons revealed polymorphism resulting from expansion and/or contraction of the micro- satellite and from indel mutations in the micro- satellite fl anking regions. As few as two primer sets were suffi cient to differentiate all unrelated introduction lines and cultivars. The primer sets failed to distinguish among closely related culti- vars developed by selection of natural variants, but one primer set uniquely distinguished the cultivar TifEagle from its irradiated parent cul- tivar. These genomic microsatellites were not derived from gene coding sequences and will supplement the existing expressed sequence tag (EST)-based bermudagrass microsatel- lites. They will be most useful for evaluating the genetic diversity of Cynodon accessions and distinguishing among cultivars that exploit this diversity.