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 × 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‐A1 null allele (Wx‐A1b) and none was found to have the Wx‐2D null allele. As described in the literature the Wx‐B1 locus was more polymorphic and the null allele was encountered in 11 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‐B1? or Wx‐B1e allele overlapping with the Wx‐D1a allele in SDS‐PAGE.