| Starch is mainly used as a staple, it is also widely used as thicker and sweetener in food and beverage industries and as raw material in paper and textile manufacture. The major component of wheat flour is starch, which accounts for about three-quarters of the composition of flour. There are two types of starch, amylose and amylopectin. Amylose is less branched, or essentially a linear glucose polymer, while amylopectin is highly branched. Owing to the presence of two kinds of glucose polymer, amylose content (%), which is significantly related with the quality of end-use wheat products, is used as one of the parameters characterizing the starch of flour. In the present study, granule-bound starch synthase (GBSS, also called waxy protein) controlling amylose biosynthesis of different wheat germplasm were studied for the clarification of their waxy protein constitution and for their better utilization in wheat breeding programs for noodle- or steamed bread-making quality.Waxy protein constitutions of 293 wheat varieties (or lines) introduced from various countries were studied by modified SDS-PAGE method. Two varieties were identified to be null Wx-Al protein, fifteen null Wx-Bl, two null Wx-Dl, two null both Wx-Al and Wx-Bl and three null all the three subunit. Fourteen materials null Wx-Bl were first discovered in this research.In order to identify different null types at thegrowing stage, PCR-based molecular markers were also used to identify waxy protein null types. According to the published cDNA sequences of Wx-Alb and genomic sequences of Wx-Ala, PCR primers were designed for specifically amplifying the deletion region of Wx-Alb. The designed primer amplified a 574bp band in the materials null Wx-Al, and a 593bp band in wild type materials. Wheat variety Yangmai158 (with Wx-Al protein) was crossed to some wheat varieties null Wx-Al protein, the primer could amplify both of the above two bands in the F1 plants, indicating that this primer was a co-dominant marker.The published PCR-based markers were also applied for identifying waxy protein types. A STS-PCR marker for Wx-Bl locus was used to identify materials null Wx-Bl protein. The identification results were coincided with that of Wx protein electrophoresis analysis. This marker was a dominant marker at Wx-B 1 locus and can be used to identify null Wx-Bl protein. A SSR-PCR marker for Wx-Al and Wx-Dl loci were used to identify materials null Wx-Al or Wx-Dl protein. This marker amplified a 265bp and a 230bp band in materials with and without Wx-Al subunit, respectively, indicating it is a co-dominant marker at Wx-Al locus. However, at the PPx-Dl locus, this marker amplified a 265bp band in materials with the Wx-Dl subunit, and lost a 204bp band in varieties null Wx-Dl subunit, indicating that it is a dominant marker at Wx-Dl locus. The above molecular markers were used to identify different null allele in FT progenies derived from yangmai 158/ waxy wheat 1. Among 100 F2 plants, 29 were null allele of Wx-Elb( null Wx-Bl summit), 7 null Wx-Dl b(null Wx-Dl summit), 1 null both alleles of Wx-Bl b and Wx-Dl b. Further research will focus on identification null allele of Wx-Al b. This Fa progeny will be used to accurately determine the amylose synthesis capacity of independent Wx gene. The identified individual plants with null Wx subunit will be used as parent in wheat breeding programs aiming to produce noodle or steamed bread-wheat.The amylose contents and swelling powers of the identified materials null different waxy proteins were determined and the relationship of the two parameters was preliminary analyzed. In average, null single allele showed no obvious amylose-content difference. However, significant variances were observed among different materials. The amylose-contents of some materials null Wx subunits showed no difference with that of Yangmai 158 or C. S. Therefore, in order to accurately determine the influence of each subunit on amylose-content, the differences of genetic background and environment must be eliminated. Among the assayed ma...
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