Waxy and low-amylose mutants of bread wheat (Triticum aestivum L.) and their starch, flour and grain properties
2006
Yasui, T.(National Agricultural Research Center for Western Region, Fukuyama, Hiroshima (Japan))
Bread wheat has three waxy proteins (= granule-bound starch synthase I, GBSSI), which are genetically controlled by three homoeologous loci, Wx-A1, Wx-B1 and Wx-D1. Several mutant lines with waxy and low-amylose endosperm were induced from cv. Kanto 107, which has two null Wx-A1b and Wx-B1b alleles and a functional Wx-D1a alleie. Starch was isolated from their grain and its amylose content, chain-length distribution profiles and thermal properties were determined. Waxy mutant lines, K107Wx1 and K107Wx2, had a new null allele named Wx-D1d on the Wx-D1 locus; a low-amylose mutant line, K107Afpp4, had a new less functional allele named Wx-D1g on the locus. Paste viscosity is markedly suppressed in waxy flour when pasting properties are measured in water using a Rapid Visco Analyzer because waxy starch swells greatly and would disintegrate at a lower temperature where alpha-amylase is still active. Flour yield of the waxy mutant lines was lower than that of Kanto 107 because the waxy lines had decreased starch content and increased fat and beta-glucan contents more than the wild type. Possible uses of the mutant lines were described from the standpoint of starch science and genetic resource.
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