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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #314362
Title: Towards the understanding of end-use quality in intermediate wheatgrass (Thinopyrum intermedium): High-molecular-weight glutenin subunits, protein polymerization, and mixing characteristics

Author
item ZHANG, XIAOFEI - University Of Minnesota
item Ohm, Jae-Bom
item HARING, STEVEN - University Of Minnesota
item DEHAAN, LEE - The Land Institute
item ANDERSON, JAMES - University Of Minnesota

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2015
Publication Date: 11/10/2015
Publication URL: http://handle.nal.usda.gov/10113/61736
Citation: Zhang, X., Ohm, J.-B., Haring, S., Dehaan, L.R., Anderson, J.A. 2015. Towards the understanding of end-use quality in intermediate wheatgrass (Thinopyrum intermedium): High-molecular-weight glutenin subunits, protein polymerization, and mixing characteristics. Journal of Cereal Science. 66:81-88.

Interpretive Summary: Intermediate wheatgrass (Thinopyrum intermedium, IWG), is a perennial crop that produces large biomass. IWG also possesses desirable agronomic traits, e.g., disease resistance, relatively large seed, and grain yield. As a perennial relative of wheat, IWG has good potential for development into a perennial grain crop. Historically used as a forage crop, however, little evaluation of the end-use quality of IWG flour was performed. To investigate the variability of end-use quality among IWG genotypes, we evaluated protein composition and mixing properties for whole grain flour samples of 60 IWG genotypes. IWG genotypes have high protein content, ranging from 16.4 to 23.6% of whole flour. Of the total proteins, the percentage of polymeric proteins that are protein fractions known to have great influence on wheat flour breadmaking quality showed large variation among IWG genotypes, varying from 9.2 to 25.1%. The protein polymers in IWG flour samples also appeared to have strong influence on gluten strength showing significant (P < 0.01) correlations with mixograph parameters, e.g., peak integral and peak time. Many IWG genotypes have limited amounts of polymeric proteins, but several genotypes have large amounts of polymeric proteins and promising mixing properties. High molecular weight glutenin subunits (HMW-GS) that are major components of protein polymers also showed large variation in the composition among IWG genotypes. Since IWG is open-pollinating, IWG grains had heterozygous HMW-GS composition. The HMW-GS variants in a group designated as TiHGS3 showed differential contribution to protein polymerization and mixograph properties. Furthermore, we observed that the composition of HMW-GS in IWG was determined by both parents, which brings challenges for the evaluation of grain quality of open-pollinated IWG genotypes. Overall, this research provides the data of quality traits and their associations with protein composition parameters for IWG genotypes grown in Minnesota. This information will benefit to the evaluation and improvement of quality and increase the breeding efficiency for IWG.

Technical Abstract: Intermediate wheatgrass (Thinopyrum intermedium, IWG), is a perennial crop that is well-known for providing good environmental services. IWG also possesses desirable agronomic traits, e.g., large biomass, disease resistance, and relatively large seed and grain yield. As a perennial relative of wheat, IWG has good potential for development into a perennial grain crop. Historically used as a forage crop, however, little evaluation of the end-use quality of IWG was performed. Here, to understand the end-use quality of IWG, we investigated the variability among 60 IWG genotypes in protein polymerization, mixograph properties and high-molecular-weight glutenin subunits (HMW-GS) using size-exclusion HPLC (SE-HPLC), Mixograph and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). IWG genotypes have high protein content, ranging from 16.4% to 23.6% of whole flour. Of the total proteins, the percentage of polymeric proteins show large variation among IWG genotypes, varying from 9.2 to 25.1%. Many genotypes have limited amounts of polymeric proteins, but several genotypes have large amounts of polymeric proteins and promising mixograph properties, comparable to bread wheat. The amount of protein polymers are significantly correlated (r = 0.76, P < 0.01) with mixograph properties, e.g., peak integral and peak time. As the major contributor to protein polymers, HMW-GS also showed large variation in the composition among IWG genotypes. Due to the heterozygosity of IWG, five to nine subunits, encoded by five HMW-GS genes and their allelic variants, were observed in individual IWG genotypes. The allelic variants of TiHGS3 showed differential contribution to protein polymerization and mixograph properties. Furthermore, we observed that the composition of HMW-GS in IWG was determined by both parents, which brings challenges for the evaluation of grain quality of open-pollinated IWG genotypes.