Characterisation of two gene subunits on the 1R chromosome of rye as orthologs of each of the Glu-1 genes of hexaploid wheat

The visco-elastic properties of bread flour are firmly associated with the presence or absence of certain HMW subunits coded by the Glu-1 genes. Ident ifying allelic specific molecular markers (AS-PCR) associated with the pres ence of Glu-1 genes can serve as a valuable tool for the selection of usefu l genotypes. This paper reports the use of primers designed from nucleotide sequences of the Glu-D1 gene of wheat (AS-PCR for Glu-D1y10) that recognis e and amplify homologous sequences of the Glu-R1 gene subunits of rye. The primers amplify the complete coding regions and provided two products of di fferent size in rye, in wheats carrying the substitution 1R(1D) and in rye- wheat aneuploid lines carrying the long arm of chromosome IR. The location, the molecular characterisation of these sequences and their expression dur ing grain ripening seem to demonstrate that the amplification products corr espond to structural genes encoding the high-molecular-weight (HMW) gluteni ns of rye. The homology of the rye gene to subunits encoding HMW glutenins in wheat was confirmed by Southern blots and sequencing. The amplification- products were cloned, sequenced and characterised, and the sequences compar ed with the main glutenin subunits of wheat and related species. Further, a n RT-PCR experiment was performed using primers designed from the sequence of both amplified products. This assay demonstrated that both sequences are expressed in endosperm. during grain ripening. The results of these analys es suggest that both gene subunits correspond to x- and y-type genes of the Glu-R1 locus of rye.