A Single Genetic Locus Associated with Starch Granule Properties and Noodle Quality in Wheat

An extensive survey of wheat cultivars showed a complete association between the presence of a granule bound starch synthase (GBSS-4A) null mutation and the classification of the respective cultivar into the white salted noodle category. Since flour swelling volume (FSV) is a standard assay of flour used to identify cultivars that have potential for the production of white salted noodles, the results of the survey were investigated further by studying the genetic association of GBSS-4A null genotypes and FSV. A study of 34, F2 derived families, from a cross between wheat cultivars Reeves (good noodle texture, high FSV) and Kulin (poor noodle texture, low FSV), provided clear evidence for the genetic association of a granule bound starch synthase (GBSS-4A) null mutation and FSV. The molecular basis for the affect of the GBSS-4A null mutation was not simply due to a decrease in amylose content in the starch granules. Instead, the null mutation most likely causes a subtle change in starch structure as indicated by the association of high starch viscosity with high FSV and the GBSS-4A null genotype. The study suggests that assaying for the GBSS-4A null mutation at the DNA level may provide a valuable screen for noodle quality at early stages in a breeding program aimed at good white salted noodle quality.