Genetic Analysis And QTL Mapping Of Dominant Earliness Of Rice Chuan 235B

Heading stage is one of the most important agronomic traits of rice,which is of great significance to localizing and cloning the genes controlling early ripening traits.In this study,the true hybrid F₁ was obtained by using the early-maturing indica maintainer line Chuan 235B,which was bred from the Crop Research Institute of Sichuan Academy of Agricultural Sciences,crossed with four late-maturing restorer lines,namely Chenghui727,Chenghui F-3,Chenghui 638 and Jinqingzhan.The genetic analysis of early-maturing trait of Chuan 235B was carried out by using four F₂ populations,and through the F₂ population of Chuan 235B/Chenghui 727 the high-density linkage map was constructed by using SNP molecular markers developed by GBS simplified genome sequencing technology,and the QTL mapping analysis was carried out for the heading stage traits of rice.The purpose of this study was to explore the QTL locus of precocity of Chuan 235B and provide molecular basis for breeding precocious varieties.The research results are as follows:（1）The precocity of Chuan 235B is controlled by incomplete dominant genes.The heading period of hybrid F₁ of Chuan 235B and Chenghui 727 was close to that of its precocious parent,indicating that the precocity of Chuan 235B was controlled by some dominant dominant genes.The heading stages of F₂ populations with Chuan 235B and Chenghui 727,Qiu F-3,Chenghui 638 and Jinqingzhan hybrid were bimodal.The Numbers of early maturing and late maturing F₂ were counted from the peak and valley,and the separation ratio of early maturing to late maturing was in line with 15:1 by chi-square test in F₂ population.The separation ratio of precocious and late maturing plants in BC₁F₁ of Chenghui 727//Chuan 235B/Chenghui 727 was 3:1.These results suggested that the precocity of Chuan 235B is controlled by two pairs of incomplete dominant genes.（2）Constructed the molecular genetic map based on GBS sequencing.GBS simplify genome sequencing technology to parents use Chuan 235B,727 and 180 to restore the F₂ segregation polymorphism analysis,obtained according to the total volume of 83.79Gb,an average of 0.46 Gb of data volume,and comparing the average rate of 81.3%,average coverage of 4.59%,average 17.94 X,cover depth development tag total 5859,including 5000 SNP marker,859 INDEL markers,by integrating after received contains5676 genetic markers in genetic map,covering a total length 1043.17 cM,the rice genome The mean genetic distance between the markers was 0.19cM.（3）QTL controlling the precocity of Chuan 235B was located.The whole genome QTL scanning was performed by WinQTLCart software based on the heading period data of180 individual plants in F₂ population.Three QTL controlling the precocity of rice were detected using LOD 3.0 as the threshold,which were located on rice chromosomes 3,5and 9.The LOD value of QTL on chromosome 3 was 4.66,the genetic variation rate was7.92%,and the confidence interval was 58.40-61.20cM.The LOD value of QTL on chromosome 5 was 5.34,the explained genetic variation rate was 8.81%,and the confidence interval was 44.20-46.30 cM.The effect value of QTL on chromosome 9 was2.04,the LOD was 3.42,the genetic variation rate was 4.99%,and the confidence interval was 59.00-65.70cM.（4）Among the three QTL detected in this study,QTL on chromosome 3 were in the same region as Ef-cd gene located by Deng Xiaojian et al.,QTL on chromosome 5 were in the same region as precocious genes located by Wang Shilei et al.,and QTL on chromosome 9 had not been reported previously.