RFLP PATTERNS OF GLIADIN ALLELES IN TRITICUM-AESTIVUM L - IMPLICATIONS FOR ANALYSIS OF THE ORGANIZATION AND EVOLUTION OF COMPLEX LOCI

A correspondence between RFLP patterns and gliadin alleles at the Gli-1 and Gli-2 loci was established in a set of 70 common wheat (T.aestivum L.) cultivars using gamma-gliadin (K32) and alpha-gliadin (pTU1) specific probes. All Gli-B1 and Gli-D1 alleles which differed in encoded gamma-gliadins showed definite RFLP patterns after hybridization with the K32 probe. Two groups of Gli-B1 alleles, Gli-B1b-like and Gli-B1e-like, were identified, and these could originate from distinct genotypes of the presumptive donor of the B-genome. Intralocus recombination and/or gene conversion as well as small deletions, gene silencing and gene amplification were assumed to be responsible for the origin of new gliadin alleles. Silent gamma-gliadin sequences were shown to exist in all of the genotypes studied. K32 also differentiated Gli-A1a from all other Gli-A1 alleles as well as the Gli-B1l allele in cultivars carrying the 1B/1R (wheat/rye) translocation. pTU1 was shown to recognize several Gli-A2 alleles, but not the Gli-B2 or Gli-D2 alleles. Moreover, this probe hybridized to chromosome 1R sequences suggesting the existence of rye gene(s), probably silent, for alpha-gliadin-like proteins on chromosome 1R.