Isolation and characterization of Glu-1 genes from the St genome of Pseudoroegneria libanotica

► We cloned four novel HMW-GS genes from Pseudoroegneria libanotica. ► All four genes were small; two of them were the smallest HMW-GS genes until now. ► They were evolutionarily older than y-type subunits didn't possess an extra Q residue. ► They represent an intermediate state in the divergence of x- and y-type subunits. ► The St genome differentiated earlier from other Triticeae genomes