Evaluation And Molecular Markers Association Study Of Rice Taste Quality Traits Based On RVA Profile

With the development of society and economy,high-quality rice varieties have played an important role in improving the production efficiency of rice and promoting the transformation of agricultural structure.In the evaluation index of rice quality traits,the taste score is an important indicator reflecting the value of rice products.The taste of rice is a complex quantitative trait,which is closely related to rice amylose content,rice appearance traits,pasting temperature and other characteristics.Its evaluation is highly dependent on artificial tasting,which greatly limits the breeding improvement of rice good taste traits.It is a key technique of studying the genetic mechanism of taste traits and breeding high-taste varieties to objectively and accurately evaluate rice food taste,which has been highly valued by the breeders.The use of RVA profile can quickly and accurately determine the starch viscosity characteristics of rice,reflect the rice starch content and texture,and take an important part in rice taste evaluation.At present,a lot of researches have been carried out study on the relationship between RVA characteristics values and the rice taste,but there are still lack of reports on the establishment of rice taste prediction models using multiple quality indicators in indica rice.In this study,the use of a wide range of germplasm materials,analysis of the relationship between RVA characteristics values and amylose content,and further use of RVA characteristic values,amylose content,rice appearance quality to build a rice food taste prediction model,in order to guide the rapid and objective identification of rice taste.Genome-wide association analysis was used to screen for candidate genes that were significantly associated with the traits which are closely related to taste,and can provide usable molecular markers for rice quality improvement.The main results are as follows:?1?The RVA profile and amylose content of 415 rice germplasms with extensive sources were tested.The results showed that the test materials had a wide range of distribution in RVA profile and amylose content.The RVA characteristic values and the AC value show a certain degree of correlation.When the AC value lies in 15-22%,it is positively correlated with the Hot paste value?HPV?,Cold paste value?CPV?,Consistency value?CS?,and Setback value?SB?of the RVA characteristic values.?2?50 rice materials of different AC levels were evaluated for their taste,and six indicators with a large correlation with taste quality were selected.we select these indexes:degree of endosperm chalkiness?x₁??length-to-width ratio of milled rice?x₂?,breakdown value?x₃??setback value?x₄??consistence value?x₅?and AC?x₆?to establish the optimal regression model by partial least squares analysis,getting the taste estimation formula as follows:y=61.8919+0.0097x₁+2.4618x₂-0.0004x₃-0.0047x₄-0.0215x₅+0.1534x₆R²=0.83,The model can better predict the rice taste.Based on high-quality Japonica rice standards and prediction models,it can be inferred that the range of physicochemical indicators of rice with a taste score above 75 is:degree of endosperm?<1.6%??length-to-width ratio of milled rice?>3.3??breakdown value?>170.3RVU??setback value?<-52.5RVU??consistence value?<122.8RVU?and AC?14-20%?.?3?We carried out a genome-wide association analysis and detected 22 SNP traits among diverse panel of 200 population cultivar.For the related sites,candidate genes were predicted and 3 cloned starch-related genes Wx,SBE1 and ALK were identified.Among them,ALK showed a P-value of 22.44 for the gelatinization temperature phenotype;In addition,7 candidate genes sites were screened out which are significantly correlated with RVA characteristic values,candidate gene Os06g0136600 possibly control of Hot paste value,Consistency value and Cold paste viscosity;Os03g08600.1 possibly control of Consistency value and Cold paste viscosity,showing a multi-effect.In this study,a regression model for predicting rice food taste was constructed,and the physicochemical traits of high-quality rice were selected.Using genome-wide association analysis,multiple traits that affected RVA characteristic values were identified and some candidate genes were screened out.The results have a strong theoretical and practical significance for the selection and breeding of high-quality rice varieties.