Interrelationships of allozymes and ribosomal DNA alleles in wild barley

A sample of 267 accessions representing almost the entire distribution range of the wild barley, (Hordeum vulgare ssp. spontaneum), was assayed for multilocus associations among two ribosomal DNA (rDNA) and seven allozyme loci. Log-linear models were constructed for three sets of data consisting of, respectively, four, three and two marker loci. The analyses established that multilocus associations of different orders are prevalent in this wild barley and the entire multilocus genetic system is organized into hierarchically structured complexes including loci located on different barley chromosomes. The results also indicated that different chromosome segments marked by various loci are not uniform in the degree of associatedness: some loci are more actively involved in interacting with each other than other loci. A comparison of these results with the previous observations in cultivated barley (H. vulgare ssp. vulgare) showed that genetic differentiation between these two taxa and among barleys from different geographical regions of the world is much larger at multilocus level than that at single locus level. The implications of these findings are discussed.