Genetic diversity in Elymus caninus as revealed by isozyme, RAPD, and microsatellite markers

Genetic diversity of 33 Elymus caninus accessions was investigated using is ozyme, RAPD, and microsatellite markers. The three assays differed in the a mount of polymorphism detected. Microsatellites detected the highest polymo rphism. Six microsatellite primer pairs generated a total of 74 polymorphic bands (alleles), with an average of 15.7 bands per primer pair. Three gene tic similarity matrices were estimated based on band presence or absence. G enetic diversity trees (dendrograms) were derived from each marker techniqu e, and compared using Mantel's test. The correlation coefficients were 0.20 4, 0.267, and 0.164 between isozyme and RAPD distance matrices, RAPD and mi crosatellite distance matrices, and between isozyme and microsatellite dist ance matrices, respectively. The three methodologies gave differing views o f the amount of variation present but all showed a high level of genetic va riation in E. caninus. The following points may be drawn from this study wh ether based on RAPD, microsatellite, or isozyme data: (i) The Icelandic pop ulations are consistently revealed by the three dendrograms. The congruence of the discrimination of this accession group by RAPD, microsatellite, and isozyme markers suggests that geographic isolation strongly influenced the evolution of the populations; (ii) The degree of genetic variation within accessions was notably great; and (iii) The DNA-based markers will be the m ore useful ones in detecting genetic diversity in closely related accession s. In addition, a dendrogram, which took into account all fragments produce d by isozymes, RAPDs, and microsatellites, reflected better the relationshi ps than did dendrograms based on only one type of marker.