GENETIC DIVERSITY OF TALL FESCUE GERMPLASM BASED ON RFLPS

The amount of genetic variation among and within tall fescue (Festuca arundinacea Schreb.) cultivars is an interest of geneticists and breed ers. However, limited information is available on this. The objective of this study was to investigate the genetic diversity of tall fescue germplasm based on RFLP data. Twenty-four probes from a tall fescue Ps tI-genomic library were hybridized to EcoRI- or HindIII-digested genom ic DNA from nine turf and seven forage cultivars, Twenty plants per cu ltivar were individually analyzed. Results showed variation within cul tivars was high, varied among cultivars and probes, and increased with the number of parental clones (PN) up to 10 and then plateaued, indic ating additional genetic variation could not be detected in cultivars with more than 10 parents. The number of bands was significantly diffe rent among cultivars and related to the within cultivar genetic divers ity, but not to the PN. Probes not hybridizing to the P genome detecte d less variation. Genetic distances calculated from 4, 8, 12, 16, and 20 plants were similar within cultivars, implying full random mating i n tall fescue cultivar development. The between cultivar genetic dista nces, however, decreased in larger sample sizes and became consistent when sample size reached 16 plants. Results suggested 16 randomly chos en plants was the minimum number to maintain adequate genetic diversit y in these tall fescue cultivars. The associations of the 16 cultivars from cluster analysis agreed with avail able pedigree information. Tu rf cultivars tended to be clustered while forage cultivars were more d ivergent.