PROTEIN FRACTION DISTRIBUTION AND THEIR CONTRIBUTION TO QUALITY CHARACTERISTICS IN WHEAT

Abstract

Wheat visco-elastic properties (Triticum aestivum L.) are mainly defined by the composition of gliadins, high (HMW-G) and low (LMW-G) molecular weight glutenins, and by the distribution of main protein fractions, monomeric (MP, rich in gliadins), soluble polymeric (SPP, rich in soluble glutenin) and insoluble polymeric (IPP, rich in insoluble glutenin). The relationship and influence of these protein fractions on rheological characteristics was examined on a set of 117 lines derived from six populations of contrasting quality. Each line had ‘Avocet’ as common female parent, and all of them grew in Sonora, México (2005-06 crop cycle). Two allelic variants in Glu-A1, Glu-B1, Glu-D1, and three in Glu-B3 loci were considered in the analysis. Overall mean distribution of the protein fraction was 42 %, 20.4 %, and 37.5 % for MP, SPP, and IPP, respectively. However, the means for the three fractions varied among the six wheat populations. The statistical analysis showed predicting values above 30% between some protein fractions and protein content, for estimation of dough mixograph traits and alveograph trait W. The effect of protein fractions distribution on wheat quality traits varied among the six genotypic populations examined. The MP showed significant correlation coefficients with dough extensibility values (Sedim-SDS and AlvP/L), while IPP correlated significantly with gluten strength data (MIXTD, %Tq, and AlvW). Determination of protein solubility distribution, Glu-1/Glu-3 allelic combinations, combined with rapid small-scale tests (protein and SDS-Sedimentation), represent a powerful selection strategy in wheat breeding to identify sources of desirable quality traits for new crosses, and later on to screen desirable quality parameters.