Allelic Variation at Glutenin Subunit and Gliadin Loci, Glu-1, Glu-3 and Gli-1, of Common Wheats. I. Its Additive and Interaction Effects on Dough Properties

Abstract

Fractionation of glutenin subunits by two-step 1-D SDS-PAGE and of gliadins by standard SDS-PAGE revealed that the parents Halberd and (W1 × MMC)/W1/10 had contrasting alleles at each of the six glutenin subunit (Glu-A3, Glu-B3, Glu-D3, Glu-A1, Glu-B1, Glu-D1) and three gliadin (Gli-A1, Gli-B1, Gli-D1) loci located on their group 1 chromosomes. Thus, a set of 74 recombinant inbred lines homozygous for these loci was chosen from a population of 280 randomly selected F3-derived F7 progeny from crosses between these parents to determine individual and combined effects of alleles at these loci on dough properties as measured by the Brabender Extensograph. The allelic effects were tested at two sites giving widely different flour protein levels, maximum dough resistance (Rmax) and dough extensibility (Ext) values; the effects were comparable between the sites as there were no major site × genotype interactions. Flour protein level generally did not vary significantly amongst the progeny groups based on alleles. On the other hand, progeny carrying alleles c and b at the low Mr glutenin subunit loci Glu-A3 and Glu-B3 had significantly greater Rmax values than the alleles e and c, respectively. Similarly, alleles i (bands 17 + 18) and d (bands 5 + 10) at the high Mr glutenin subunit loci Glu-B1 and Glu-D1 , respectively, gave greater Rmax values than the alleles e (band 20) and a (subunits 2 + 12). Alleles at the other loci (Glu-D3 and Glu-A1) did not give significantly different Rmax values. The effects of individual Glu-3 or Glu-1 alleles on Rmax were largely additive, thus together accounting for about 80% of the variability in Rmax among these progeny. Interactions (epistasis) between different Glu-3 and/or Glu-1 loci also affected Rmax significantly, accounting for about another 10% variation. Based on the alleles analysed, different glutenin subunit loci could be ranked as Glu-D1 > Glu-B1 > Glu-B3 > Glu-A3 > Glu-D3 = Glu-A1 with respect to Rmax . In contrast to Rmax, only 25% of the variation in extensibility could be accounted for by the glutenin alleles. Only Glu-D1 and Glu-D3 loci showed significant effects on this parameter.