Fine Mapping For Restorer Gene Of The RN Type Cytoplasmic Male Sterility Of Soybean

CMS is widespread in nature.Male sterility plant is often an unfavorable trait for plants in the process of biological evolution and reproduction.But breeders use this trait to creat two method of cross breeding named "two lines" and "three-line". These methods has become two of the important ways of utilization of heterosis.Soybeans are self-pollinated crops.So it needs to be emasculated during hybridization.This process is very cumbersome, detasseling stigma might cause damage, and often resulting in more pseudo-hybrids. This is not conducive to large-scale hybrid seed production, and would limit the use of soybean heterosis.Soybean "Three Lines" hybridization method is the main way of heterosis utilization.In order to meet the need of the industrial seed production,we need to use the sterile line and the restorer line to make a large-scale portfolio allocation to find the strong heterosis screened during this process.The utilization of the Cytoplasmic male sterility fertility restorer gene is the theoretical basis of the three-line hybrid seeds for cytoplasmic male sterility. The main focus is to find varieties with stable resilience. However, restorer line breeding is extremely cumbersome.The structure and molecular mechanism of restorer gene of corn, morning glory, rice, carrots and other crops has been extensively studied and cloned. Although cytoplasmic male sterility in soybean breeding has been widely used, but the markers and the mechanism of action on soybean cytoplasmic male sterility restorer gene studies have rarely been reported.This study have completed the following Experiment:(1)We use JLCMS9 A × JLR102 constructed RN soybean cytoplasmic male sterility backcross introgression lines and found that all of the F1 samples are semi-sterile. F2 is separated fertility, and contains 90 fertile plants, 109 semi-sterile plants.The fertility segregation ratio close to 1: 1. It means that this trait is consistent with the typical genetic characteristics of gametocytes single gene control.(2)To improve the efficiency and accuracy of the restore gene mapping, we divided the material into two categories, the fertile group and the semi-sterile group.We randomly selected 20 DNA samples from two fertility pools and equally mixed into two pools, then, coupled with sterile DNA gene pool. Finally, we used the three gene pools to screening primers of restore gene targeting.(3)We choose the classic SSR core primers to amplify the gene pool, and got a well performed polymorphic SSR marker: BARCSOYSSR-16-1165.This primer marker loci locates on the XVI chromosome of soybean. According to this conclusion, we have redesigned 101 pairs of SSR primers and screened them again. Finally we got six pairs SSR primer showed good polymorphismbet between fertility mixing pools. They are BARCSOYSSR-16-1062, BARCSOYSSR-16-1065, BARCSOYSSR-16-1095, BARCSOYSSR-16-1102, BARCSOYSSR-16-1123, BARCSOYSSR-16-1165. We build the genetic map by Joinmap 4.1, and the results showed that the restorer gene Rf is between BARCSOYSSR-16-1065 and BARCSOYSSR-16-1095, genetic distance to SSR markers BARCSOYSSR-16-1062, BARCSOYSSR-16-1065, BARCSOYSSR-16-1095, BARCSOYSSR-16-1102, BARCSOYSSR-16-1123, BARCSOYSSR-16-1165 are 6.1 c M, 2.3 c M, 1.3 c M, 3.1 c M, 3.3 c M and 5.4 c M.(4)This target region contains seven genes that encode putative pentatricopeptide repeat(PPR)proteins.These genes have the same structure with the restorer genes. The eight PPR protein-encoding ORFs are clustered together at the sixteenth chromosome. We speculated that these genens may be the candidate restorer genes of Rf. However, this experiment has not verified the function of these eight genes, so We need to continue in-depth study...