Mapping Of QTL For Rice Grain Quality And Cooking Characters

In order to explore favorable alleles and provide theoretical basis for the genetic improvement of rice quality,a chromosome segment substitute line(CSSL)population,which were constructed by Changhui 121,a odor type indica variety,and Koshihikari,a superior grain quality japonica variety,was used to analyse correlation and QTL of the rice quality traits in 4 environments.The main results are as follows:1.Gel consistency and protein content of rice showed significant or very significant correlation with multiple RVA characteristics in four environments.There is a significant correlation between the RVA characteristics.The related traits of cooked rice include water absorption rate,elongation rate,expansion rate showed a significant or very significant positive correlation with each other,but did not have significantly correlation with quality triats.The sensory value of rice was significantly positively correlated with gel consistency,grain surface area,peak viscosity and breakdown viscosity,but negatively correlated with amylose content,chalkiness percentage,final viscosity and setback viscosity.2.A total of 44 QTL for 11 quality traits were detected in 4 environments.There QTL included 4 QTL for chalkiness rate,4 QTL for gel consistency,2 QTL for protein content of rice,and 34 QTL for other rice starch viscosity.q HPV6,q BDV6,q CPV6,q SBV6-1,q CSV6 were identified in 4 environments.q PGWC1 was identified in three environment.q Pa T6-1,q Pa T12 were identified only in two environments.These QTL were further confirmed across three or four different environments by some chromosome segment substitute lines.Multiple QTL were mapped on the same loci or near region of a linkage group.The two major clustered QTL were located on chromosomes 6 near gene Wx and SSSI.This phenomenon was caused by multiple closely linked genes or multiple effects of one gene? It would be needed to understand by the further fine mapping and gene cloning.3.Four QTL for related traits of cooked rice,including 1 QTL for water absorption rate,2 QTL for elongation rate,1 QTL for expansion rate were detected in 2016 by using composite interval mapping analysis.q WA8 for water absorption rate coincides and q CRE8 for elongation,q CRE11 for elongation and q VE11 for expansion rate were detected on the same location,respectively.q CRE11 and q VE11 were first detected in our study.One QTL for retrogradation was mapped in RM1369～RM510 of chromosome 6,this region covered Wx gene.Path analysis of sensory quality of rice using chalky grain rate,gel consistency,protein content,amylose content,grain surface area,pasting temperature,water absorption rate,elongation and expansion ratio,showed that these 9 factors accounted for only44.39% of the sensory quality of rice,and only the direct path coefficient between amylose content and taste value of rice sensory showed a significant level.This showed that there are other factors affecting sensory eating quality of rice and would be needed to further explored,and that using amylose content as a selection trait to screen high quality rice is feasible.