Relationships Between Wheat Glutenin Polymers And Processing Quality And Their Response To Nitrogen And Environments

Wheat glutenin has an important effect on processing quality. Up to now, wheat protein has been divided into different fractions with various extraction schemes and analysis methods. A large number of studies have been made on the fractions especially on wheat glutenin. However, most of the protein fractionation procedures were based on traditional Osbome extracting method. All these fractionation procedures generate quite large, partly overlapping classes of protein. Each class consists of a broad range of protein. So it's very difficult to grasp the essence of the fractions., A new extracting method with 1-propanol was used in recent study, so that determination of different fractions was avoided. Glutenin polymers could be extracted exactly from flour protein and divided precisely into different fractions,providing an effective method for studying the relationships between glutenin fractions and functionality for processing. In this article, we developed a rapid method for quantitative of glutenin macropolymer (GMP) and soluble glutenin protein (SGP) largely based on the new 1-propanol extracting technique .The new fractionation procedure was applied to analyzing a large number of wheat samples to evaluate the content of glutenin polymers and their size distributions for Chinese wheat varieties; to determine the relationships between glutenin polymers and processing quality parameters; to analyze the variation types of Glu-1 loci which dominate the major components (HMW-GS) of glutenin polymers and the effect of the types on glutenin polymers through HMW-GS(s); to deeply study the response of glutenin polymers to increased nitrogen fertilization and effects of growing location on the content of glutenin polymers and their size distribution for different wheat varieties. The main results as follows:1. The 1-propanol/biuretium flour protein fractionation procedure based on the differential solubility of wheat flour protein in different aqueous solutions of 1-propanol yields three protein fractions, one monomeric in nature and two polymeric fractions corresponding to soluble glutenin, insoluble glutenin. Quantitative of the fraction wasmade with improved biuret reaction. This procedure can effectively avoid glutenin fraction from contamination with other protein fractions generated by traditional Osborne fractionation scheme. This procedure was simple and rapid with good reproducibility and much practical value for discerning protein quality differences among different genotypes particularly in relation to dough mixing requirements.2. The analysis of amounts and distributions for different glutenin fractions among 126 representation of common wheat cultivars and new lines growing in main wheat production zones of China showed that the range of GMP concentrations in flour among the genotypes was 1.70~6.60% with mean value of 3.87%; the concentrations of GMP in flour protein ranged from 17.26% to 41.87% with mean value of 31.21%; the mean concentration of SGP in flour was 1.75% which accounted for 14.32% of flour protein; the concentrations of total glutenin polymers in flour protein ranged from 53.86% to 52.19% with mean value of 45.53%; the intercultivar variations in the concentrations of GMP in flour and GMP and SGP in flour protein were all at a high levels, larger than that of the concentrations of SGP in flour. This indicates that GMP, GMP/Pr and SGP/Pr are mainly genotypic characteristics with significantly different levels in the genotypes.3. The concentration of total glutenin polymers in flour proteins was significantly related to processing quality. The higher the concentration of glutenin in flour protein was, the higher of the GMP content and the lower of the SGP contentexisted. Both GMP and SGP have an effect on breadmaking quality, but act in an opposite direction. GMP content in flour and in flour protein affect positively on good processing quality attributes and SGP negatively.SGP/Pr has stronger effect on the attributes than SGP does. GMP, GMP/Pr, SGP and SGP/Pr have linear...