Rht-1 semi-dwarfing alleles increase the abundance of high molecular weight glutenin subunits

Background and Objectives Grain protein and starch abundance and composition are quantitative traits that play key roles in wheat quality. The semi-dwarfing alleles of the Reduced height (Rht-1) gene increase tillers and yield but also reduce seed size and protein content. Despite their negative impact on grain protein content, the semi-dwarfing alleles increase dough mixing time and tolerance. This study used near isogenic lines that were either tall or semi-dwarf lines that carried Rht-B1b, Rht-D1b, or Rht-8 to investigate how each semi-dwarfing allele impacts gluten composition and flour pasting properties. Findings None of the semi-dwarfing alleles impacted starch properties. Each reduced flour protein content compared to the tall variety with the largest decreases in Rht-B1b (1.8%) and Rht-D1b (1.5%). The semi-dwarfing lines increased the gluten index (21.5%) compared to Rht-1a. Using SE-HPLC, we determined that the semi-dwarfing lines had an increased relative abundance of high molecular weight glutenins compared to the tall variety. Conclusions This study indicates that the Rht-1 semi-dwarfing alleles increase dough mixing time and tolerance by increasing the relative abundance of high molecular weight glutenins yielding stronger dough. Significance and Novelty The semi-dwarfing alleles developed primarily for agronomic purposes have significant impacts on gluten index and starch swelling power.

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