Study On The Phenotypic Variation And QTL Mapping Of Important Agronomic Traits For Two Main Restorer Lines Of Rice(Oryza Sativa L.)

Main restorer line is a kind of rice restorer lines which has been widely used in hybrid rice breeding practice.The study on the genetic basis of main restorer lines and identification of QTL/gene underlying important agronomic traits will facilitate the breeding application of restorers by the molecular marker assisted selection in rice.In this study,the population with 250 recombinant inbred lines(RILs)was developed with main restorer lines Chenghui727 and 9311 as parents.The phenotypic identification and QTL mapping analysis of nine agronomic traits were conducted in Sanya and Hefei.In order to provide a theoretical reference for the improvement of main restorer lines and molecular breeding,the identification of the elite genes of Chenghui727 and 9311 and the dissection of the genetic basis of yield and related traits in restorer lines also were conducted.The main results are as follows:1.All traits of RILs were basically normal distribution.Several differences of those traits of the population were observed in Sanya(SY)and Hefei(HF),which indicated that the environmental factors had influences on the growth of rice.2.The results of correlation analysis showed that there were several differences for the correlations among all the traits in two environments,and the differences were larger in some traits,even with positive or negative directions.The correlation of heading date between Sanya and Hefei is not significant,which is similar as FGP and GY.This result showed that the environmental difference between Sanya and Hefei had some influences on the growth of rice.3.The results of variance analysis showed that the variance of the variation source(genotype,environment,genotype and environment interaction)of all the traits reached the extremely significant level(P<0.001).The results indicated that not only the genetic factor influence the phenotype of all traits,but the environment factor and the interaction between genotype and environment also have a extremely significant influence on the phenotype of all traits.In comparison of the general heritabilities of nine traits,we found that the general heritabilities of nine traits range from 45.20% to 72.32%,in which the general heritability of PL is the maximum,72.32%,and the general heritability of GY is the minimum,45.20%.This result indicated that both the genetic factor and the environment factor have influences on phenotype.4.The result of QTL mapping showed that a total of 39 QTLs were detected in Sanya and Hefei environments.Sixteen QTLs were detected in Sanya,which located on chromosome 1,2,4,7,8,10,11 and 12;and 24 QTLs were detected in Hefei,which located on chromosome 1,2,3,7,8,9,10 and 12.Only QTL qPH1-1 can be detected in both Sanya and Hefei environments.The favorable alleles of 24 QTLs derived from Chenghui727 and 15 QTLs from 9311.A main QTL qHD8-1 controlling HD may be Ghd8.Five multiple effect QTLs were detected in the marker interval RM279—RM521,RM336—RM3534,RM25—RM547,RM553—RM160,RM222—RM271.The QTL located in 2 cM marker interval between RM553 and RM160 controlling FGP,GY and SF is a novel multiple effect QTL.Two novel QTL qPL2-1 and qSF3-1 were located in 1.1 cM marker interval between RM213 and RM482 and 1.8 cM marker interval between RM520 and RM293,and there are 106 and 109 predicted genes in the target regions,respectively.These QTLs located in 2 cM marker interval facilitate the further fine mapping and deep identification of the elite genes of main restorer lines,and the new pleiotropic QTLs provide valuable materials for molecular marker assisted breeding.