Suppression of Rye Omega Secalins and Related Wheat Proteins in a Wheat Variety Carrying a 1BL.1RS Translocation

The contributions of individual seed proteins and protein families to wheat end-use properties can be revealed by comparing flours prepared from closely related genotypes that differ in the presence/absence of those proteins. Genetic engineering allows us to make specific changes in wheat seed protein composition. We applied an RNA interference (RNAi) strategy to assess how rye proteins affect the end-use properties of wheat cultivars, such as ‘Bobwhite’, that carry a translocation between the group 1 chromosomes of wheat and rye.  Those translocations bring in the Sec-1 locus from rye and the omega and gamma secalin storage proteins it encodes. An RNAi vector was constructed with a promoter from a wheat high-molecular-weight glutenin gene driving expression of sense and antisense copies of 500 bp of the coding region from an omega secalin gene. Introduction of the RNAi construct into ‘Bobwhite’ by biolistic transformation resulted in major decreases in several 40-50 kDa seed proteins, shown by proteomic analyses to be rye secalins and omega gliadins, the wheat proteins most closely related to the secalins. The levels of some other seed proteins were affected, but to a lesser extent. Measurements of mixing properties revealed that doughs from two different transgenic flours were stronger and had higher mixing tolerance than those from the non-transformed parent. These studies show that genetic transformation is a useful way to change the levels of seed proteins and protein families so that their contributions to wheat quality can be measured in near-isogenic backgrounds.