Development of a panel of specific monoclonal antibodies to high molecular weight glutenin subunits and their application in genetic screening

High molecular weight glutenin subunits (HMW-GS) encoded by different chromosomal loci and alleles (1, 2, 5, 7, 10, and 12) were purified using reversed-phase HPLC from reduced, aqueous propanol extracts of flour from aneuploid or null wheat lines. Unlike previous libraries of monoclonal antibodies developed in our laboratory to SDS-extracted or alkylated HMW-GS, several of the monoclonal antibodies (mAb) developed in this study had a range of specificity patterns for HMW-GS in enzyme-linked immunosorbent assay (ELISA) and on immunoblots. A subset of the mAb bound either x- or y-type HMW-GS but not other gluten proteins, while a few antibodies bound one (mAb 110622, 110421, 140820), or two (mAb 101319, 110804, 140705, 1410460) HMW-GS expressed in each cultivar tested. In most cases, antibodies bound equally to the subunits encoded by different HMW-GS alleles. The more specific antibodies should be useful in research on the quantitative variation of HMW-GS expression and in studies of the role of particular HMW-GS in dough structure. The mAb 101319, which was prepared to subunit 1, bound to HMW-GS 1Bx subunits in ELISA and on immunoblots. This antibody also provided a higher absorbance value in ELISA with extracts of wheat lines expressing the Glu-Ble allele (HMW-GS 20) compared with the Glu-Bli allele (HMW-GS 17+18). Another mAb (110622) detected subunit 2 more strongly than subunit 5 in ELISA and produced a higher signal in immunoblots with subunit 2 even though these subunits are > 98.7% homologous in amino acid sequence. An ELISA assay using this antibody was optimized for discrimination of wheat lines with the allelic pairs of subunits lD x 5-1Dy 10 from those with 1D x 2-1Dy 12, with the former lines providing stronger dough properties and superior breadmaking quality. The performance of this assay was unaffected by other variations at HMW-GS loci and was demonstrated in sets of biotypes, doubled haploid, and cross-bred breeder's lines.