QTLs Mapping For Stigma Exsertion And Protein Content In Rice

Rice protein as a kind of high quality plant protein, can affect human health. Therefore, it’s of theoretical and practical significance to characterize the quantitative trait loci (QTLs) to improve rice protein content and develop high quality rice varieties satisfying different needs.Rice, one of the most important model plants in botany research, is explored the genetic basis of its stigma exsertion which can lay a research foundation of revealing the key events in the process of cultivated rice domestication. Meanwhile, rice, as an important food crop, can be greatly improved the efficiency of hybrid seed production by means of ameliorating its stigma exsertion, especially female parent in hybrid combination, which will undoubtedly bring great economic benefits.In this research, we constructed a genetic linkage map of recombinant inbred line population from Yuezaoxian No.6/Ⅱ-32B, and then used the phenotype value of stigma exsertion and unpolished rice protein content of F9and F10generations to characterize quantitative trait loci (QTLs) controlling stigma exsertion and unpolished rice protein content. We analyzed the relationship between the unpolished rice protein content and heading stage, rice chalkiness rate. The results of my research are as follows:1. The genetic linkage map construction:we used Yuezaoxian No.6to screen polymorphism markers with parent II-32B. A total of146SSR markers were finally available to construct a linkage map. The whole length of the map was1086.2cM, and the average distance was10.86cM between adjacent markers.2. The relationship between protein content and chalkiness rate, heading date:the correlation coefficient of2011protein content (PC11) and2011chalkiness rate (CR11) was-0.02, and2012was-0.06. The protein content phenotype in two years had no obvious correlation with chalkiness rate phenotype. The correlation coefficient of2011protein content (PC11) and2011heading date (HD11) was-0.45, and2012was-0.45. The protein content phenotype in two years had obvious negative correlation with heading date phenotype. Meanwhile, the qPC6-1locus controlling protein content and qHD6-2locus controlling heading date co-localized between RM584(RM585)-RM314 on the chromosome6, which also demonstrated genetic correlation between protein content and heading date from the gene level.3. The protein content QTL mapping:Based on the phenotype data of protein content of RILs from both2011and2012, a total of6quantitative trait loci (QTLs) affecting protein content were detected on chromosomes6,7,8and10, respectively. And single QTL explained5.70%-17.56%phenotype variance. The qPC6-1was repeatedly detected between RM584and RM314on chromosomes6in the two years, the LOD value were5.57and3.36, the additive effect were1.89mg/g and1.47mg/g, the contribution rate to explain the genotype variance were13.17%and10.97%in both years. And the gene effect derived from Yuezaoxian.4. The chalkiness rate QTL mapping:Based on the phenotype data of chalkiness rate of RILs from both2011and2012, a total of6quantitative trait loci (QTLs) affecting chalkiness rate were detected on chromosomes5,6, and7, respectively. And single QTL explained6.87%～38.71%phenotype variance. The qCR5-1and qCR6-2was repeatedly detected on chromosomes5and6in the two years. The LOD value of qCR5-1were4.13and4.93, the additive effect were9.91%and11.01%, the contribution rate to explain the genotype variance were6.87%and10.23%in both years; the LOD value of qCR6-2were16.53and12.65, the additive effect were20.92%and16.45%, the contribution rate to explain the genotype variance were38.71%and27.06%in both years. The gene effect both derived from Ⅱ-32B.5. The stigma exsertion QTL mapping:Based on the results of stigma phenotypes of RILs from both2011and2012, a total of16quantitative trait loci (QTLs) affecting stigma exsertion were detected on chromosomes1,3,5,6,7and9, respectively. Single QTL interpretable phenotype variation was5.08%-35.72%. These QTLs were mainly distributed between RM472-RM12276section on chromosome1and RM278-RM107section on chromosome9. Interval RM472-RM12276interpretable phenotype variation were10.65%-35.72%, the gene effect derived from Ⅱ-32B. Interval RM278-RM107interpretable phenotype variation of14.40%-43.59%, the gene effect derived from Yuezaoxian. In a word, the positioned QTLs provide related genetic basis for rice quality improvement and seeding efficiency enhancement of sterile line by MAS.