Study On The Cause For Quality Diversity Of Wheats With Same HMW-GS And The Access Of Improving Wheat Quality

HMW-GS composition is closely correlated with wheat quality. Based on the quality effect of HMW-GS variation, some scoring systems were developed. Glu-Dl 5+10 was always given high attention among the scoring systems and employed as important marker in wheat breeding for high quality. With this marker some high quality varieties were developed. Some varieties, however, are poor quality although they have 5+10 and high HMW-GS score. On the other hand, the wheat varieties with 5+10 showed different quality levels. Two main wheat cultivars with 5+10 planted in Heilongjiang set a good example since their quality performed great difference among different years and tween the cultivars. In this study we employed some wheat varieties with same HMW-GS background and different quality characteristics to investigate reasons of wheat quality difference. Meanwhile we also studied genetic manipulation and crop cultivation measure to raise wheat quality so that we can support wheat breeding and cultivation with theory base for high quality. The study items and results are as follow. 1. Quality difference analysis of wheat varieties with same HMW -GS composition.Four strong gluten wheat varieties with 5+10 and same HMW-GS composition showed Longfu970189>Longmai 26>Long94~4081>Longfu98N2 in protein and wet gluten (reflecting quantity of protein) and Long94-4081>Longmai 26>Longfu970189>Longfu98N2 in sedimentation value (reflecting quality and quantity of protein). On the sensitivity to fertilization, Longmai 26>Long94-4081>Longfu98N2>Longfu970189 in the variation range of protein and wet gluten content. Based on the quality indices we can conclude that Longmai 26 and Longfu970189 are better than Long94-4081 and Longfu98N2 in quality. Although Longmai 26 showed good quality, its quality stability is lower than Longfu970189. High and stable quality are targets of wheat production, however, Longfu970189 should be planted in proper proportions since its earliness and lower yield.In the process of grain filling, Longmai 26 and Longfu970189 showed higher accumulation of HMW-GS compared with Long94-4081 and Longfu98N2. The accumulative quantity and proportion of Glu-Dl 5+10 in Longmai 26 and Longfu970189 are higher than that of Longfu98N2. The Glu-Dl 5+10 accumulation quantity in Long94~4081 is the lowest among the four varieties although its 5+10 proportion is the highest that may be one of the reason caused quality difference. The accumulative dynamics of wheat LMW-GS is contrary to that of HMW-GS, theaccumulative quantity of Long94~4081 and Longfu98N2 is higher in different fertilization levels while that of Longmai 26 and Longfu970189 is lower . In the ratio of HMW-GS and LMW-GS, Longfu970189(0.94)>Longmai 26(0. 85)>Longfu98N2(0.59)>Long94-4081(0.51). Higher quantity of LMW-GS and lower ratio of HMW-GS/LMW-GS may be one of the reason caused normal quality but high sedimentation value in Long94~4081.During the period of grain filling, Long94-4081 has the highest a and P gliadin content and proportion while Longmai 26 and Longfu970189 have the highest y gliadin content and proportion . In wgliadin content and proportion, the varieties keep the order of Longfu98N2>Longfu970189>Long94-4081>Longmai 26.With the same background of HMW-GS, the strong gluten varieties showed difference in the content of large molecular polymer. The LMP of Longfu970189 and Longmai 26 is obviously higher than that of Long94-4081 and Longfu98N2, indicating that good quality variety or lines have high level of LMP and vice versa . Its changing trend is also identical to that of HMW-GS. Therefore we think that the formation of large molecular polymer keeps closer relation with HMW-GS content.Wheat quality is very complicated. Varieties performed very different quality even if they have high quality subunits and same HMW-GS composition. The reason could be explained in a extent by the accumulation and compositions proportion of HMW-GS and gliadin, as well as large molecular polymer content. However, further study is needed to clarify the f...