BIOCHEMICAL AND GENETIC-CHARACTERIZATION OF A D-GLUTENIN SUBUNIT ENCODED AT THE GLU-B3 LOCUS

The SDS-PAGE pattern of reduced and alkylated glutenins from the bread wheat cultivar Prinqual presents a subunit (named d(4)) in the mobili ty zone of the omega-gliadins that only appears under reduced conditio ns. This subunit was isolated and characterised at the biochemical and genetic levels. Subunit d(4), was shown to form disulphide aggregates with glutenins and had an acidic pi. These characteristics correspond to those of the D glutenin subunits. The N-terminal amino acid sequen ce of subunit d(4), was coincident with the SRL sequence type characte ristic of omega-gliadins encoded by genes on the 1B chromosome, and co nfirms the similarity between D glutenin subunits and omega-gliadins. The genetic study of subunit d(4), was performed in the F-2 progeny fr om the 'Prinqual' x 'Ablaca' cross, based on four prolamin loci: Glu-B I, Glu-B3, Gli-B1, and Gli-BS. The recombinants found between Glu-B3 a nd Gli-B1 demonstrated that subunit d(4), was encoded at the Glu-B3 lo cus, and reinforces the hypothesis of the duplication of prolamin gene clusters in wheat. A preliminary study of the effect of subunit d(4), on gluten strength showed that lines with the Glu-B3 allele from 'Pri nqual', which includes subunit d(4),, had a significantly higher sedim entation volume than those with the allele from 'Ablaca'.