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

Authors: JOBSON, EMMA - Montana State University; Ohm, Jae-Bom; MARTIN, JOHN - Montana State University; GIROUX, MIKE - Montana State University

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2020
Publication Date: 11/18/2020
Citation: Jobson, E., Ohm, J., Martin, J., Giroux, M. 2020. Rht-1 semi-dwarfing alleles increase the abundance of high molecular weight glutenin subunits. Cereal Chemistry. https://doi.org/10.1002/cche.10371.
DOI: https://doi.org/10.1002/cche.10371

Interpretive Summary: The wheat Rht-1 genes function to decrease plant height and increase the number of plant stems and therefore help to increase grain yield. However, there is little information available regarding how the Rht-1 genes might affect processing and end-use quality traits. Therefore, this research was performed to investigate how the Rht-1 genes impacted processing and end-use quality traits of wheat cultivars that carry them by evaluating grain protein content and starch abundance and composition. The Rht-1 genes did not impact starch properties. However, the cultivars with Rht-1 genes had lower protein content in their flour, but they had better protein composition, which resulted in stronger gluten when compared to cultivars that did not carry the Rht-1 genes. These results imply that the Rht-1 genes function to enhance processing and bread-making quality by improving protein composition. Overall, this research indicates that, although the genes were incorporated into wheat cultivars to improve agronomic performance, they have significant impacts on processing and bread making quality as well.

Technical Abstract: Grain protein and starch abundance and composition are quantitative traits that play key roles in dough rheology. 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 dough rheology. 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. 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. The semi-dwarfing alleles developed primarily for agronomic purposes have significant impacts on dough rheology and bread making.