Genetic Analysis And Gene Mapping Of The Photoperiod-Thermo Sensitive Genic Male Sterile Rice Line DS

Two-line heterosis breeding based on the photoperiod-thermo-sensitive genic male sterile (P/TGMS) has the main advantages including the ability of using a wide range of genotypes as male parents, absence of negative effects associated with sterility-inducing cytoplasm, no need for maintainer lines, and created a new way for the use of heterosis. The low-threshold temperature is the most important technical indicators of the breeding of two-line sterile line. The characteristics of DS, low infertility threshold temperature (≤23.0℃), high stigma exsertion rate and high outcrossing rate, indicating that DS is the photoperiod-thermo sensitive genic male sterile line for northern rice area and could be used as the parent of the breeding of two-line sterile line.Fertility expression and percentage of exserted stigmas (PES) were investigated under the conditions of high temperature in Tianjin using a population of F2plants derived from a cross between a high-PES variety DS and a low-PES variety C9083and then analyzed and gene mapped for sterile gene and stigma exsertion rate of DS by simple sequence repeat(SSR) and Insertion and deletion(InDel) techniques.Genetic analysis used the F2population derived from a cross between the DS and C9083indicated that the sterilety of DS was controlled by a single recessive gene, which showed qualitative traits, the stigma exsertion of DS was in conformity with normal distribution, which showed quantitative trait.Molecular mapping was performed on the F2mapping population using SSR and InDel makers and bulked segregant analysis(BSA). The sterility gene located on chromosome2. A whole genome linkage genetic map containing101makers was constructed by QTL IciMapping V3.0, with total length of1942.68cM on whole genome. The average distance between makers19.23cM. Sixteen QTLs distributing on the seven chromosomes were detected for stigma exsertion rate based on the F2population of DS/C9083. The additive effects played major roles in most quantitative trait loci.Five QTLs (qPSES-1a, qPSES-3a, qPSES-7a, qPSES-7b. qPSES-9a) for percentage of single exserted stigma were located on chromosome1.3,7and9, respectively. The qPSES-1a locus QTL was the most significant which LOD score was18.28with phenotypic variation explained by37.62%. Four QTLs (qPDES-3a, qPDES-6a, qPDES-9a, qPDES-11a) for percentage of double exserted stigma were located on chromosome3,6,9and11, respectively. The qPDES-3a locus QTL was the most significant which LOD score was14.99with phenotypic variation explained by31.18%.Seven QTLs (qPES-1a, qPES-3a, qPES-3b, qPES-7a, qPES-7b, qPES-9a, qPES-Wa) for PES were located on chromosome1,3,7,9, and10, respectively. The qPES-3b locus QTL was the most significant which LOD score was19.69with phenotypic variation explained by41.91%. All the three additive allele genes with top3LOD score were from DS. Single stigma exsertation and total stigma exsertation were detected in qPSES-7a and qPSES-7b locus on chromosome7. The qPDES-3a locus in which the double stigma exsertation and total stigma exsertation was detected and the qPSES-3a locus in which Single stigma exsertation was detected were overlap indicating that the two loci may be controlled by the same gene. In molecular marker-assisted breeding, we can try to use above positioning results to achieve the directional cultivation of the high stigma exsertion parent.This study provides valuable reference for fine mapping, gene cloning and marker-assisted selection (MAS) of the sterility gene and stigmas exserted gene.