The Study On Genetic Characteristic And Selection On Resistant Starch-linked Ssr Marker In Wheat

Resistant starch (RS) is the sum of starch not absorbed by amylase in the small intestine. It's the focus of carbohydrate researches recently, and the unique physical function of RS has aroused many researchers'concern. The development and exploitation of RS molecule marker technology will reduce the cost and workload of RS determination, overcome the blindness and raise the efficiency of selecting, and provide theoretical basis to the breeding of wheat varieties with high RS content. While the foundation of molecular marker assisted selection of these varieties will be built too. In our experiment, M344 and Wuchun3 whose RS content was most significant were used as parents to develop F₂ generations. A SSR(Simple sequence repeats)marker conferring high resistant starch content was searched by BSA (bulked segregant analysis) method. The main results were as follows:1,A appropriate method of the resistant starch (RS) testing which suitable for most laboratories was established based on the method of AOAC2002.2 and Goni(1996), combined with our laboratory's condition. 172 spring wheat germplasm resources from worldwide were determined by this method. The results showed that the average content of resistant starch in wheat kernel was 2.01%. Among the 172 spring wheat varieties, the highest was 3.07% (M344, from Mexico) and the lowest was 0.54% (Wuchun3, from Gansu). T-test showed that the RS content of M344 and Wuchun3 were most significant (P<0.01). Using M344 and Wu-chun3 as cross-parents to develop inherit generations for RS content molecular marker selection. Preliminary discussions were made on the separation and distribution of F₂ generation's RS contents. The average content was 1.27%, between the two parents. The inheritance of F₂ generation was inclined to the low parent and the lower parent heterosis was significant. The resistant starch content of F₂ generation showed a continuous variation and approximated to normal distribution, the skewness coefficient (0.546%) and the peak (0.176) were all bellow 1.2,The analysis of correlation among some major quality parameters (resistant starch content, amylose content, total starch content, swelling power, Zeleny-sedimentation value, dry and wet gluten content, peak viscosity and through viscosity ) of 172 spring wheat germplasm resources showed that the resistant starch content positively correlated with amylase content (significantly at 0.01 level, r=0.60), also total starch content,swelling power and peak viscosity (significantly at 0.05 level, r=0.31, 0.28 and 0.27, respectively), and negatively with dry and wet gluten content (however not significantly, r= -0.03 and r= -0.16, respectively). Amylase content , total starch content,Zeleny-sedimentation value,peak viscosity and swelling power affected resistant starch content were further screened by stepwise regression analysis, and the regression equation can provide a 42.2% explanation for the phenotypic variations.3,By the RS content determination of F₂ generation plants, a SSR marker Xbarc59 conferring high resistant starch content was searched by bulked segregant analysis (BSA) method and a specific fragment of 170bp appeared among high RS content materials. In F₂ generation, SSR primer Xbarc59 was closely correlated to RS content, and the amounts of RS was different significantly (0.01 level) among the three genotypes: high-parent type, heterozygote and low-parent type. Respectively, the average content of higher and lower RS individuals differentiated by Xbarc59 was 1.44% and 0.99%, and the difference was most significant (0.01level). So the primer Xbarc59 could be an available molecule marker to select the wheat breeding materials with high RS content.