Towards the understanding of end-use quality in intermediate wheatgrass (Thinopyrum intermedium): High-molecular-weight glutenin subunits, protein polymerization, and mixing characteristics

•Intermediate wheatgrass has larger amount of seed proteins versus common wheat.•Gluten proteins in intermediate wheatgrass can form large protein polymers.•Intermediate wheatgrass genotypes show high diversity in mixing characteristics.•Composition of HMW-GS in intermediate wheatgrass was contributed by both parents.

Intermediate wheatgrass (Thinopyrum intermedium; IWG), is a perennial crop that is well-known for providing good environmental services. As a perennial relative of wheat, IWG has good potential for development into a perennial grain crop. But the diversity and potential of the end-use quality of IWG grain are still unknown. Here, to understand the end-use quality of IWG, we investigated the variability among seed from 60 IWG genotypes in high-molecular-weight glutenin subunits (HMW-GS), protein polymerization, and mixing characteristics. IWG genotypes have high grain protein content, ranging from 16.4 to 23.6%. Of the total proteins, the percentage of polymeric proteins show a large range across 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 mixing properties, comparable to common wheat, Triticum aestivum. The amount of protein polymers in the SDS buffer unextractable fraction are significantly correlated (r ≥ 0.76) with mixograph parameters. Furthermore, we observed that HMW-GS variants showed differential contribution to protein polymerization and mixograph parameters. But the composition of HMW-GS in IWG was contributed by both parents, which might bring challenges for the evaluation of grain quality of open-pollinated IWG genotypes.