Variation of starch granule proteins and chromosome mapping of their coding genes in common wheat

Starch granule proteins (SGPs) of common wheat (Triticum aestivum L.) were analyzed by two electrophoretic techniques: sodium dodecyl sulphate polyacrylamide-gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2D-PAGE). These analyses identified three kinds of SGPs which were tentatively designated SGP-1, SGP-2 and SGP-3. SDS-PAGE resolved the products of three homoeologous genes for SGP-1 into three protein fractions, SGP-A1, -B1 and -D1. While SDS-PAGE resolved SGP-3 into one fraction, 2D-PAGE separated it into three protein fractions encoded by homoeologous genes Sgp-A3, B3 and -D3. SGP-2 was detected as one protein by SDS-PAGE and was present as one protein on 2D-PAGE. Aneuploid (nullisomic-tetrasomic and ditelosomic) analyses in the cultivar Chinese Spring showed that the genes for two SGPs (SGP-1 and -3) were located on the short arms of group-7 chromosomes. The results obtained from deletion lines for chromosome arms 7AS, 7BS and 7DS suggested that the gene order along the arms is 'centromere-Sgp-1-Sgp-3-Wx'. An electrophoretic survey of wheat germ plasm identified a few cultivars lacking one of the proteins SGP-A1, -B1, -D1, SGP-A3 and -B3. The null alleles Sgp-A1b, Sgp-B1b and Sgp-D1b will be useful for the production of a variant wheat lacking SGP-1.