Quantitative variation in high molecular weight glutenin subunit 7 in some Canadian wheats

Abstract

Gradient SDS-PAGE analysis of some Canadian wheat cultivars and breeders' lines revealed that there was variation in the mobility of the high molecular weight (HMW) glutenin subunit 7. One group of cultivars/lines had a subunit 7 band that was comparable to that found in the cultivar Chinese Spring, whereas another group had a slightly more mobile band comparable with the subunit 7 band in Bezostaya. This latter band was designated as HMW glutenin subunit 7* in order to differentiate it from the subunit 7 component present in cultivars such as Chinese Spring. Reversed-phase high-performance liquid chromatographic (RP-HPLC) analysis showed that subunits 7 and 7* had comparable elution times. Quantitatively, the proportion of subunit 7 relative to the total amount of HMW glutenin subunits was significantly higher (41·2± 1·5 %) than subunit 7* (27·1 ±0·9 %). The relative proportions were consistent within each group of cultivars as indicated by low coefficients of variation, 3·6 and 3·4 %, respectively. Similarly, the absolute peak area, on a per cent protein basis, was significantly higher for subunit 7 than for subunit 7*. Subunit 7* was found in combination with subunit 9 or subunit 8 or a variant of subunit 8 (as determined by RP-HPLC) designated subunit 8*. This indicated that there are at least three alleles controlling this subunit. Subunit 7 was present in combination with subunits 8 or 8*, and thus there are at least two alleles controlling this subunit. Subunit 7 may be associated with greater dough strength and decreased extractability of gluten proteins. The identification, therefore, of these subunits could be useful for selection purposes in a wheat breeding program.