ALLELIC VARIATION AT GLUTENIN SUBUNIT AND GLIADIN LOCI, GLU-1, GLU-3 AND GLI-1 OF COMMON WHEATS .2. BIOCHEMICAL BASIS OF THE ALLELIC EFFECTS ON DOUGH PROPERTIES

The biochemical basis of allelic effects of different glutenin subunit loci (Glu-A3, Glu-B3, Glu-D3, Glu-A1, Glu-B1, Glu-D1) and gliadin loci (Gli-A1, Gli-B1, Gli-D1) on dough strength (as measured by Brabender Extensograph or National Mixograph) was studied in a set of 74 recombinant inbred lines from two sites (thus, 148 lines) and in certain biotypes differing only for high Mr glutenin alleles (subunits 5 + 10 and 2 + 12) at the Glu-D1 locus. The relative size distributions of polymeric proteins (native glutenin) and the quantities of glutenin subunits, gliadins and albumins/globulins were determined using SE-HPLC and RP-HPLC/SDS-PAGE. The data revealed that the low Mr glutenin subunit alleles (b and c) at the Glu-B3 locus and alleles (c and e) at the Glu-A3 locus, giving significantly different Rmax (Extensograph maximum resistance) values, produced B type of low Mr glutenin subunits in different amounts and affected size distribution and/or quantity of the polymeric protein. On the other hand, the alleles at the Glu-B1 and Glu-D1 loci produced high Mr subunits (viz. 17 + 18 and 20 or 5 + 10 and 2 + 12) in similar quantities and only caused differences in the size distributions of the polymeric proteins. Thus, differences other than the quantity of these subunits (e.g. size or polymerising behaviour) are responsible for the different effects of the alleles at the Glu-B1 and Glu-D1 loci on Rmax or MDDT (Mixograph peak dough development time). The relative size distribution of polymeric protein alone could account for all the individual (main effect) and combined (additive and interaction effects) effects of different alleles on dough strength. The quantities of gliadins did not account for the positive effects associated with Glu-3/Gli-1 alleles on dough strength. © 1994 Academic Press Limited.