Molecular Characterization And Evolutionary Analyses Of Resistance Genes At Soybean Rsv3Locus Conferring Resistance To Soybean Mosaic Virus

Soybean mosaic virus (SMV) is one of the most destructive viral diseases in soybean around the world and affecting soybean [Glycine max (L.) Merr.] production worldwide. To date, many studies have been conducted to elucidate the inheritance of resistance to SMV in soybean. Three resistant locus to SMV have been reported, Rsv1,Rsv3and Rsv4. Rsv3has mapped between markers A519F/R and M3Satt in the soybean molecular linkage group B2(chromosome14), and has been characterized by examination of the soybean genome sequence. The154kbp interval encompassing Rsv3contains a family of closely related coiled-coil nucleotide-binding leucine-rich repeat (CC-NB-LRR) genes, including Glyma14g38500, Glyma14g38510, Glyma14g38540, Glyma14g38560and Glyma14g38590.We designed primers according to5’UTR and3’UTR of these five genes in Rsv3locus, and then amplified the whole genes in Rsv3locus from10soybean genetypes, Kefeng No.1, Qihuang No.1, Davis, Kwanggyo,8101, Youbian30, Nannong1138-2, Juxuan, Zaoshul8, Columbia. All the PCR products were sequenced, and finally we got46sequences form all these soybean genotypes. Among which there are1014g38500,1014g38510,914g38540,714g38560and1014g38590. Through the46and5genome gene sequences comparing and phylogenetic analyzing, we found that the5genes homologous sequeces in10soybean genetypes on Rsv3locus could be divided into two groups. The first group contains14g38500and14g38510, which maintain high consistency among10soybean germplasms. The other group contains14g38540,14g38560and14g38590. The three genes display obvious sequence differences, the mutations may be resulted by positive natural selection. DNA sequeces analysis and phylogenetic and recombination analysis tell that14g38540may be the candidate resistant gene on Rsv3Locus. Because in the SMV resistant genetypes Zaoshul8and Columbia on Rsv3locus, they display consistent mutations at14g38540and all lose the homologous sequeces of14g36560. The most surprising thing is that the14g38540in Zaoshul8and Columbia are recombinants, and the recombinants may be prodused by the gene conversion or unequal crossover between the14g38540and14g38560ancestor sequences.