New insight into the function of wheat glutenin proteins as investigated with two series of genetic mutants

Among the three major food crops (rice, wheat and maize), wheat is unique in accumulating gluten proteins in its grains. Of these proteins, the high and low molecular weight glutenin subunits (HMW-GSs and LMW-GSs) form glutenin macropolymers that are vital for the diverse end-uses of wheat grains. In this work, we developed a new series of deletion mutants lacking one or two of the three Glu-1 loci (Glu-A1, -B1 and -D1) specifying HMW-GSs. Comparative analysis of single and double deletion mutants reinforced the suggestion that Glu-D1 (encoding the HMW-GSs 1Dx2 and 1Dy12) has the largest effects on the parameters related to gluten and dough functionalities and breadmaking quality. Consistent with this suggestion, the deletion mutants lacking Glu-D1 or its combination with Glu-A1 or Glu-B1 generally exhibited strong decreases in functional glutenin macropolymers (FGMPs) and in the incorporation of HMW-GSs and LMW-GSs into FGMPs. Further examination of two knockout mutants missing 1Dx2 or 1Dy12 showed that 1Dx2 was clearly more effective than 1Dy12 in promoting FGMPs by enabling the incorporation of more HMW-GSs and LMW-GSs into FGMPs. The new insight obtained and the mutants developed by us may aid further research on the control of wheat end-use quality by glutenin proteins.