Fine Mapping Of R_SC7 And R_SC13 And Evaluation Of Resistance Gene Pyramidings

Soybean Mosaic Virus（SMV）disease is a widely spread viral disease of global soybean[Glycine max（L.）Merr.]production areas,which causes serious harm to seed yield and quality.Developing new resistant varieties is the most economical and effective control efficiency to SMV disease.As a result of the dynamic changes of local SMV strain and the emergence of new strain,the research of soybean varieties with sustainable broad-spectrum resistance to SMV has become the key to solve this urgent problem.With a set of differential varieties,21 SMV strains have been classifiedamong the Chinese SMV isolatse at the Nanjing Agricultural University.This study aimed at genetic analysis of resistance to popular strains SC7&SC 13 and fine mapping of the resistance gene in Kefeng NO.1.According to theWilliams82 whole-genome shotgun sequence（WGS）of soybean,it will be more clear that relevant information of candidate resistance genesand the resistance mechanism of these genes.In addition,the agronomic characters and the resistance to SMV of the progeny of SMV resistance gene pyramiding was under investigation.All of the results could not only work for cloning of resistance genes and transgenic disease-resistant varieties foundation,but also provide SMV resistance breeding system with excellent resistance germplasm.The main results were as follows:1.Analysis of inheritance of Rsc7and Rsc13With the recombined inbred lines（RILs）and F2 of secondary population（SP-F2）groups of Kefeng No.1 x Nannong 1138-2,by inoculation with SC7 and SC13 strains,results of the chi-square test showed that the separation of the RILs population was 1 resistance:1 susceptible in ratio and the segregation ratio of SP-F2 group was 1 resistance:2LS:1 susceptible,which could be summarized to this:Kefeng No.1 resistant to SC7 and SC 13 strain were controlled by a pair of genes separately.2.Fine mapping of Rsc7RILs population（184 families）and SP-F2（116 individual plants）ofKefeng No.1 x Nannong 1138-2were inoculated with SC7.With the analysis of simple sequence repeats（SSR）markers,results showed thatRsc7 was located between BARCSOYSSR₀2₀667 and BARCSOYSSR₀2₀670 on chromosome 2（MLG Dlb）.The genetic distance of the two closest markers was 0.7cM.What’s more,the physical distance ofthe interval was about 77 kb,which contained one LRR gene and another transcription factorofF-box region.3.Fine mapping of RSCI3With Kefeng No.1 × Nannong 1138-2 RILs population（184 families）and SP-F2（128 individual plants）inoculated with SC13,two SSR markers（BARCSOYSSR 02 0610 and BARCSOYSSR 02 0621）were closely linked toSC13 resistant gene.The physical distance whereRsc13waslocated was about 191 kb.The sequence anliysis showedthere were double K-box region type of transcription factors,GM HSP40 and two serine/threonine protein kinase（STK）genes.4.Evaluation of the progeny of resistance gene pyramidingsThis research was to make a survey of F7 progeny of five resistance gene pyramidings（GPR5-1-5）,which derived from the multicross of the donars[Dabaima（RSC4）,Kefeng No.1（RSC8）,Qihuang No.1（RSC14Q）and Nannong 1138-2（susceptible to SMV）]and was slected by marker assisted slection（MAS）.After the investigation of the agronomic characters,it showed some agronomic traits of GPR5-1-5 plant were worse than that of the four parents,but GPR5-1～5 have got different increase in most of the agronomic traits.During the inculation with SMV in greenhouse,GPR5-1-5 showed resistant to not only SC4,SC8 and SC 14,but also the other 18 SMV strains,which showed resistance spectrum of GPR5-1-5 was broader than that of he four parentsrespectively.The results proved that the use of MAS for resistance gene pyramiding breeding can be applied to the practice of breeding of resistance to SMV.