Genetic Diversity of Tall Fescue Germplasm Based on RFLPs

Abstract

The amount of genetic variation among and within tall fescue (Festuca arundinacea Schreb.) cultivars is an interest of geneticists and breeders. 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 PstI‐genomic library were hybridized to EcoRI‐ or HindIII‐digested genomic DNA from nine turf and seven forage cultivars. Twenty plants per cultivar were individually analyzed. Results showed variation within cultivars was high, varied among cultivars and probes, and increased with the number of parental clones (PN) up to 10 and then plateaued, indicating additional genetic variation could not be detected in cultivars with more than 10 parents. The number of bands was significantly different among cultivars and related to the within‐cultivar genetic diversity, but not to the PN. Probes not hybridizing to the P genome detected less variation. Genetic distances calculated from 4,8,12,16, and 20 plants were similar within cultivars, implying full random mating in tall fescue cultivar development. The between‐cultivar genetic distances, however, decreased in larger sample sizes and became consistent when sample size reached 16 plants. Results suggested 16 randomly chosen plants was the minimum number to maintain adequate genetic diversity in these tall fescue cultivars. The associations of the 16 cultivars from cluster analysis agreed with available pedigree information. Turf cultivars tended to be clustered while forage cultivars were more divergent.