New insights into high-molecular-weight glutenin subunits and sub-genomes of the perennial crop Thinopyrum intermedium (Triticeae)

Intermediate wheatgrass (Thinopyrum intermedium) is a perennial crop that possesses desirable agronomic traits and provides environmental services, e.g., reducing soil erosion, nitrate leaching and inputs of energy and pesticide. Thus, intermediate wheatgrass is currently being domesticated as a perennial grain crop. However, the genetic information for molecular breeding is quite limited. Here we report a molecular analysis of high-molecular-weight glutenin subunits (HMW-GS) in intermediate wheatgrass using gene cloning and protein biochemistry. Five HMW-GS genes were isolated from individual intermediate wheatgrass plants: two x-type genes TiHGS1 and TiHGS4, and three y-type genes TiHGS2, TiHGS3 and TiHGS5. Among them, TiHGS5 was novel and possessed an additional cysteine residue at the N-terminal domain or repetitive domain. Sequence alignments showed that TiHGS1 and TiHGS2 genes shared high identities (>96%) with the Glu-1Dx and Glu-1Dy genes, respectively, in common wheat and Aegilops species, TiHGS3 with HMW-GS genes from Dasypyrum or Pseudoroegneria, and TiHGS4 and TiHGS5 with HMW-GS genes from Thinopyrum elongatum. This work provides substantial new insights into the gene compositions and protein profiles of HMW-GS in intermediate wheatgrass, and also gives evidence about the genome components of intermediate wheatgrass.