Study On Starch Properties And Molecular Markers Of Waxy Gene In Wheat

Starch is mainly used as a staple, it is also widely used as thicker andsweetener in food and beverage industries and as raw material in paper andtextile manufacture. The major component of wheat flour is starch, whichaccounts for about three-quarters of the composition of flour. There are twotypes of starch, amylose and amylopectin. Amylose is less branched oressentially 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, isused as one of the parameters characterizing the starch properties.Starch properties are the important factors to determine noodle quality.1D-SDS-PAGE eletrophoresis and molecular markers were employed tosurvey the Waxy proteins and Waxy genes in 227 winter wheat cultivars andadvanced lines from different Chinese Provinces and cities and foreigncountries, 30 lines selected from the cross of Jinmai66 and Wx1 which weredetected preliminarily to be waxy wheat with Iodine-dyeing-seed-section.Amylose content and RVA properties were also recorded. The major resultswere presented as follows:1 The components of waxy protein subunits could be detected precisely by1D-SDS-PAG Eelectro- phoresis. In total, 15 and 6 cultivars and advancedlines with null Wx-B1 were presented in Chinese wheats and foreigncuitivars respectively. Totally 30 lines from the cross of Baihuomai andNorin 67 were real waxy wheats.2 3 molecular markers could be used to detect different Waxy genes. Theprimer 1 could amplify one diagnostic band of about 327bp to the irregularWx-7A. The Primer 2 could amplify one diagnostic band of about 440bp tothe regular Wx-4A. The primer 3 could amplify one diagnostic band of about204bp to Wx-7D, and showed polymorphisms to Wx-7A for different cultivars and lines.3 Significant variantions in starch properties were observed. The variancecoefficient of swelling power, peak viscosity, hold through, break down andfinal viscosity for Chinese wheat was 18.16%,28.48%,43.45%,19.57% and35.10%, respectively. A very significant negative correlation was observedbetween amylose content and each RVA parameter except pasting temprature.The correlation coefficients were 1% or 5%. The difference for swellingpower, break down and final viscosity between 15 cultivars with null Wx-B1and the others with normal subunits was at 5% significant level. Comparedwith good quality noodle wheats from Austrilia, significant variation wasobserved in starch properties in Chinese wheats and the range for amylosecontent, swelling power, peak viscosity, hold through, break down, finalviscosity and setback was 17.79～28.75%, 3.77～10.45g/g, 491.50～4497.00cP,74.00～3042.00cP, 548.50～1986.50cP, 69.00～5142.50cP, 123.00～2185.00cP,respectively.4 Significant differences in RVA properties between waxy wheats andnon-waxy wheats were observed, break down were higher than non-waxywheats, but peak viscosity, hold through, final viscosity, setback and peaktime were clearly lower than non-waxy wheats.