Contributions of individual and combined Glu-B1x and Glu-B1y high-molecular-weight glutenin subunits to semolina functionality and pasta quality

Authors: ZHANG, YAZHOU - University Of California, Davis; SCHONHOFEN, ANDRE - University Of California, Davis; ZHANG, WENJUN - University Of California, Davis; HEGARTY, JOSH - University Of California, Davis; CARTER, CLAUDIA - University Of California, Davis; VANG, TENG - University Of California, Davis; L Chingcuanco, Debbie; DUBCOVSKY, JORGE - University Of California, Davis

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2020
Publication Date: 3/2/2020
Citation: Zhang, Y., Schonhofen, A., Zhang, W., Hegarty, J., Carter, C., Vang, T., Chingcuanco, D.L., Dubcovsky, J. 2020. Contributions of individual and combined Glu-B1x and Glu-B1y high-molecular-weight glutenin subunits to semolina functionality and pasta quality. Journal of Cereal Science. 93. https://doi.org/10.1016/j.jcs.2020.102943.
DOI: https://doi.org/10.1016/j.jcs.2020.102943

Interpretive Summary: Durum wheat is mainly ground to make semolina for pasta production. The high-molecular-weight glutenin subunits (HMW-GS) encoded by the closely linked genes Glu-B1x and Glu-B1y are known for their combined effects on pasta quality. To understand the individual contributions of Glu-B1x and Glu-B1y, we compared the effect of mutations in each gene or both genes on pasta quality relative to wild-type. We found that loss the of Glu-B1x ('Bx6) and Glu-B1y ('By8) gene products were associated with significant reductions in gluten strength, with the loss of proteins encoded by both genes ('Bxy ) having the most effect. Reductions in gluten strength were reflected in reduced mixograph and alveograph parameters, faster extrusion flow rates and increased cooking loss. Interestingly, the Glu-B1x mutation was also associated with significant increases in grain and semolina protein content, increased pasta firmness, reduced starch viscosity and increased amylose in 'Bx6 and 'Bxy. In general, the 'Bx6 mutation had stronger effects than the 'By8 mutation. In addition to the basic knowledge gained on the individual effect of the Bx6 and By8 subunits and their interactions on pasta quality, the genetic stocks developed in this study provide useful tools to study the effects of natural or synthetic HMW-GS on pasta quality parameters in a background lacking endogenous HMW-GS.

Technical Abstract: Durum wheat is an important food crop used primarily for pasta production. High-molecular-weight glutenin subunits (HMW-GS) encoded by the closely linked genes Glu-B1x and Glu-B1y are known for their combined effects on pasta quality, but their individual contributions and interactions remain poorly understood. In this study, we show that individual loss-of-function mutants of Glu-B1x ('Bx6) and Glu-B1y ('By8) were associated with significant reductions in gluten strength compared to the wildtype, with stronger effects in the 'Bxy double mutant. Reductions in gluten strength were reflected in reduced mixograph and alveograph parameters, faster extrusion flow rates and increased cooking loss. Interestingly, the Glu-B1x mutation was also associated with significant increases in grain and semolina protein content, increased pasta firmness, reduced starch viscosity and increased amylose in 'Bx6 and 'Bxy. In general, the 'Bx6 mutation had stronger effects than the 'By8 mutation, and significant interactions between the two genes were frequent. In addition to the basic knowledge gained on the individual effect of the Bx6 and By8 subunits and their interactions on pasta quality, the genetic stocks developed in this study provide useful tools to study the effects of natural or synthetic HMW-GS on pasta quality parameters in a background lacking endogenous HMW-GS.