Comparative diversity analysis of RFLPs and isozymes within and among populations of Hordeum vulgare ssp. spontaneum.
Zhang, Q., M. A. Saghai Maroof and A. Kleinhofs. 1993. Genetics 134:909-916.
ABSTRACT DNA restriction fragment length polymorphisms and isozyme variation were surveyed in 268 accessions of the wild barley Hordeum vulgare ssp. spontaneum sampled from a diversity of ecogeographical ranges in Israel and Iran. A total of 15 probes, which detected 17 putative loci, were selected to include three classes (single, low/multiple copy and repetitive) of DNA sequences representing all seven barley chromosomes, and the isozymes were alleles of seven well characterized loci. The results clearly established that both RFLPs and isozymes were highly polymorphic both within and among populations of this wild barley. The number of alleles per locus and the average level of diversity did not appear to be different between isozymes and RFLPs. However, the relative amounts of within vs. between population components differed greatly between isozymes and RFLPs. Isozyme markers demonstrated larger amount of within population diversity, whereas RFLPs resolved higher proportion of between population differentiation. Furthermore, RFLPs detected much more heterozygosity than did isozymes. Both RFLPs and isozymes resolved large numbers of multilocus combinations, and majority of these multilocus combinations were represented by only one individual in the total sample. Individuals within populations differ from each other by as much as 30% of the loci, and plants in different populations differ from each other in about 50% of the loci. Many of the important aspects of the population diversity are significantly correlated between isozymes and RFLPs. However, such correlation values are in general low indicating that only a small proportion of the genetic variation detected by one class of markers can be predicted by the other class of markers.