Characterization of high molecular weight glutenin subunit genes from the Ns genome of Psathyrostachys juncea

The Ns genome of the genus Psathyrostachys possesses superior traits useful for wheat improvement. However, very little is known about the high molecular weight (HMW) subunits of glutenin encoded by the Ns genome. In this paper, we report the isolation of four alleles of HMW glutenin subunit gene from Psathyrostachys juncea. Sequence alignment data shows the four alleles have similar primary structure with those in wheat and other wheat-related grasses, with some unique modifications. All four sequences more closely resemble y-type, rather than x-type, glutenins. However, our results show three of the subunits (1Ns2-4) contain an extra glutamine residue in the N-terminal region not found on typical y-type subunits, as well as the x-type subunit specific sequence LAAQLPAMCRL. These three subunits likely represent an intermediate state in the divergence between x- and y-type subunits. Results also indicate that the Ns genome is more closely related to the St genome of Pseudoroegneria than any other Triticeae genomes.