Common Wheat Grain Yield and Bread-Making Quality Are Affected By Mutations in SBEII Genes

Starch with high proportion of amylose in common wheat (Triticum aestivum) is correlated with increased content of resistant starch, a fermentable dietary fiber that can provide health benefits. To develop wheat kernels with high resistant starch content, induced mutations in STARCH BRANCHING ENZYME II (SBEII) genes were incorporated in the hexaploid wheat cultivars Lassik and Patwin-515. This study aimed at quantifying the effect of the SBEII mutations on common wheat grain yield, as well as on grain, flour, starch and bread quality parameters. In two replicated field trials, we observed that mutations in the genes SBEIIa (A, B and D genomes) and SBEIIb (A and B genomes) conferred large increases in amylose (~60%) and resistant starch content (~1000%). SBEII mutations were also associated with decreased kernel weight (~3%), flour extraction rate (~21%), grain yield (~6%) and loaf volume (~26%). Incremented flour protein content, water absorption and altered flour viscosity parameters can be favorable depending on the end-product desired. Significant interactions for several quality properties were detected between cultivar and/or environments, indicating that some of the negative effects of the SBEII mutations could be ameliorated through careful selection of the genetic background and location for deployment of the trait. Economic incentives will likely be necessary to motivate growers to use varieties with high resistant starch content in view of the observed reductions in grain yield.