Investigation Of The Effects Of Starch Synthesis Related Genes On Rice (Oryza Sativa L.) Qualities Using Near Isogenic Lines

With the improvement of people’s living standards,as well as consumer demand for rice quality changes,good quality has become an important goal of rice breeding.A large number of study have shown that the cooking and eating quality of rice is determined by the composition and structure of the starch.Therefore,the research of the effects of starch synthesis related genes on the physicochemical characteristics of rice will provide an important clue for the improvement of rice quality.In the present study,a set of near-isogenic lines(NILs)of amylopectin synthesis-related genes developed previously in our laboratory,were employed,which was generated with an indica cultivar Guichao2 as recurrent parent crossing to a japonica cultivar Suyunuo,as nonr parent,by continuous backcrossing and molecular marker-assisted selection.The genetic background and agronomic traits of NILs were investigated,and the physicochemical characteristics of starch(AAC,RVA and DSC)were measured,and then the genetic effects of the amylopectin synthesis related genes were anylyzed.The main results are as follows:1.Three kinds of polymeric materials were obtained by hybridization with single gene NILs,which is NIL-SSⅡ-2/SSⅡ-3.NIL-SSⅢ-1/SSⅢ-2 and NIL-ISA/PUL.2.The results of main agronomic traits and genetic background tests showed that the genetic background of each pair of NILs was basically consistent with that of Guichao2,and the main agronomic traits were very similar to Guichao2.This results indicated that the NILs was successful developed,and it provides an ideal material for studying the effects of amlopectin synyhesis related genes on the physicochemical characteristics of rice starch.3.AAC assessment results showed that there is a certain difference between the recurrent parent and the NILs.The differences between NIL-SSⅡ-2,NIL-SSⅢ-2,NIL-SSⅡ-2/SSⅡ-3 and recurrent parent were statistically significant or extremely significant,indicating that the differentiation of indica-japonica alleles on SSⅡ-3 and SSⅢ-2 loci had a greater and more stable genetic effect on AAC.4.DSC characteristics analysis showed that NIL-SSII-3,NIL-SSII-2/SSII-3 have a significant or extremely significant differences in thermodynamic characteristics compared to those of the recurrent parent,and the effects were observed to be stable in different environments.Japonica allele on SSⅡ-3,SSⅡ-2/SSⅡ-3 significantly increased the peak temperature(Tp),initial temperature(T0),termination temperature(Tc),heat enthalpy(△H).The results of multiple comparisons of single gene NILs and polymeric gene NILs can be shown that the Japonica allele on SSII-3 had a stable genetic effect on the gelatinization characteristics,Indica and Japonica subspecies allele differentiation is obvious,Polymerization gene of SSII-2 and SSII-3 had no synergistic effect in the gelatinization characteristics.5.The results of the RVA characterisitics measurments showed that the amylopectin synthesis related genes had a significant effect on the RVA profile,SSII-3 and SSIII-2 were differentiated between Indica and Japonica,and the fine structure of starch had a great influence,combined with multiple comparison results for single gene NILs and polymeric gene NILs.