Allelic variants of granule-bound starch synthase proteins in European bread wheat varieties

The composition of 324 European wheat cultivars were analysed at the three granule-bound starch synthase (GBSS I) loci. Protein separation was first made by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). A specific two-dimensional (2D) electrophoresis (immobilized pH gradient x SDS-PAGE), using an Immobiline dry strip in the first dimension was developed to resolve the GBSS I proteins more clearly and to confirm some results. Very low polymorphism was found. Among the 324 cultivars analysed, only one carried a Wx-A 1 null allele (Wx-A1b). and none was found to have the Wx-D1 null allele. As described in the literature, the Wx-B1 locus was more polymorphic, and the null allele was encountered in 1 I cultivars. The use of 2D electrophoresis allowed us to find another type of variant which presented as having thicker band with same mobility as the Wx-D1 protein in SDS-PAGE. Twelve per cent of the cultivars analysed presented this band and could have been previously mistaken for cultivars carrying the Wx-B1 null allele. Indeed, this band probably corresponded to the Wx-B1c' or Wx-B1e allele overlapping with the Wx-D1a a allele in SDS-PAGE.