| Resistant Starch(RS)is a functional starch that has the functions of regulating diabetes,blood lipid and intestinal health.As an important food crop,rice(Oryza sativa L.)has nearly90%starch,but the RS content of most rice varieties is often less than 3%,which can not meet the needs of people.Recently,the research of RS in rice has become an important part of rice breeding research.In this study,73 rice materials were used to identify the genotypes of 18 starch synthesis-related genes(SSRGs)and determine the RS conent in raw milled rice,cooked rice and retrograded rice.Association analysis was employed to clarify the effects of SSRGs and their interactions on different types of RS content.At the same time,the physicochemical properties of rice materials were determined.The correlation between RS content and physicochemical indices,RVA profile characteristics and thermal characteristics were analyzed to explore the relationship between RS content and physicochemical properties,so as to provide useful information for molecular breeding of rice RS.Moreover,the recombinant inbred lines(RIL)was selected to investigate the effects of some SSRGs on the RS content and verify the results of association analysis.The main results are as follows:1.RS content in three sample types showed a wide variations among the 73 rice materials.And RS content decreased dramatically after cooking,but it did not increase significantly after cooling for 7 days,indicating that the subtype of RS in the materials was mainly RS2,and less RS3.2.Physicochemical properties of the 73 rice materials differed significantly,and the correlation between RS content and most of physicochemical properties were significant at0.05 or 0.01 level.3.A total of 159 alleles were detected by 42 pairs of SSR markers in 73 rice lines,with an average of 3.786 polymorphic loci detected by each pair of marker.The genetic basis of 73rice materials was abundant and showed moderate polymorphism.Cluster analysis based on genetic similarity coefficient showed that the tested lines could be divided into four groups.The analysis of population structure indicated that the optimal subgroup number of population was four.Some lines had a relatively pure genetic background,but most of the lines with the mixed background because of the cross of ancestral subgroups.4.The results of association analysis showed that RS in rice was regulated by several SSRGs.There were five genes involved in the genetic regulation of RS in raw milled rice,which were Wx,SSII-2,SSIV-2,SSII-3 and SSI,and their genetic effects decreased in turn.Wx,SSI,GBSS II,SSII-2 and PUL were associated with the variation of RS in cooked rice.RS in retrograded rice was affected by Wx,SSI,SSII-2 and GBSS II.Wx,SSII-2,SSIV-2,SSII-3 and SSI had effects on RS2,and the genetic effects of Wx and SSII-2 were the most significant.There were three genes involved in the genetic regulation of RS3.Their genetic effects were Wx>SSII-2>SSIV-2.The genes involved in the genetic regulation of different types of RS,and partial genes only had effect on a type of RS,which indicated the complexity of RS genetic mechanism.5.There were significant interactions among different SSRGs on RS of different proceeding types.Among them,the interaction between Wx and SSII-2 had significant effects on different types of RS,which further indicated the complexity of genetic mechanism of RS.6.In the RIL populations,Wx had a great effect on RS content and Wx~acould elevate RS content in different processing status of rice.The different SSII-3 alleles result in the variation of RS in raw rice and indica SSII-3(SSII-3i)could enhance RS content in raw milled rice and RS2.Apart from RS3,the combined effects of Wx and SSII-3 greatly affected other types of RS.Wx~a-japonica SSII-3(Wx~a-SSII-3j)is favorable to forming large-diameter starch granules. |
PDF Full Text Request