Abstract
Starch is the major component of the bread wheat (Triticum aestivum L.) grain and its properties affect the quality of wheat flour and flour products. The amylose content is a principle factor influencing starch properties. K107Afpp4 is a low-amylose mutant line induced from cv. Kanto 107 showing an altered flour-pasting profile on measurement with a Rapid Visco Analyzer (RVA). Its RVA profile is characterized by a markedly increased viscosity at a lower temperature and a decreased peak time. The allelic state of the Wx-D1 locus in K107Afpp4 was clarified by assuming Mendelian segregation of the trait. The RVA profile of the mutant was governed by a single major gene, which was partially dominant to that of its wild type, Kanto 107, and also to that of the backcrossed waxy line with the genetic background of Kanto 107. These results indicated that the gene responsible for the characteristic RVA profile of the mutant is located on the Wx-D1 locus and other loci are unrelated to the trait, suggesting a new allele on the Wx-D1 locus, which is designated Wx-D1g. Since the band intensity of the waxy protein (GBSSI) from K107Afpp4 starch was unaltered from that of the wild type, the waxy protein of the mutant presumably has a structure different from that of Kanto 107 and is probably less functional than that of the wild type.
