SEED-STORAGE-PROTEIN LOCI IN RFLP MAPS OF DIPLOID, TETRAPLOID, AND HEXAPLOID WHEAT

Linkages between high-and low-molecular-weight (M-r) glutenin, gliadin and triticin loci in diploid, tetraploid and hexaploid wheats were st udied by hybridization of restriction fragments with DNA clones and by SDS-PAGE. In tetraploid and hexaploid wheat, DNA fragments hybridizin g with a low-M-r glutenin clone were mapped at the XGlu-3 locus in the distal region of the maps of chromosome arms 1AS, 1BS, and 1DS, A sec ond locus, designated XGlu-B2, was detected in the middle of the map o f chromosome arm 1BS completely linked to the XGli-B3 gliadin locus. T he restriction fragments mapped at this locus were shown to co-segrega te with B subunits of low-M-r glutenins in SDS-PAGE in tetraploid whea t, indicating that XGlu-B2 is an active low-M-r glutenin locus. A new locus hybridizing with the low-M-r clone was mapped on the long arm of chromosome 7A(m) in diploid wheat, No glutenin protein was found to c o-segregate with this new locus, Triticin loci were mapped on chromoso me arms 1AS, 1BS, and 1DS, A failure to detect triticin proteins co-se gregating with DNA fragments mapped at XTri-B1 locus suggests that thi s locus is not active. No evidence was found for the existence of Gli- A4, and it is concluded that this locus is probably synonymous with Gl i-A3. Recombination was observed within the multigene gliadin family m apped at XGli-A1 (1.2 cM). Although these closely linked loci may corr espond to the previously named Gli-A1 and Gli-A5 loci, they were tempo rarily designated XGli-A1.1 and XGli-A1.2 until orthology with Gli-A1 and Gli-A5 is established.