Mapping Of Resistance Gene To Phytophthora Sojae In Soybean And Analysis Of Candidate Genes

Phytophthora root rot(PRR),caused by the soil-borne oomycete pathogen Phytophthora sojae,could infect soybean at any growth period and reducing yield seriously.Deploying resistant cultivars remains the most effective and economical approach to managing this disease.Screening resistance soybean was the manner of choosing elite resource,and identifying resistance gene was the main channel for studying molecular mechanism.In this study,the resistance reaction of 337 Yangtze-Huai soybean breeding line population(YHSBLP)to three P.sojae was analyzed,combining SNPLDBs and SNP marker to find the resistance locus by association mapping.The genetic analysis of resistant gene in Meng8206 was carried out by secondary population and the linkage mapping was constructed using SSR markers.Cloning and preliminary bioinformatics analysis of genes that may be involved in disease resistance.These results will contribute to understand the genetic mechanism and molecular mechanism of soybean Phytophthora root rot,and also help the molecular marker assisted selection(MAS)in soybean breeding.1.Identification of Phytophthora resistance in YHSBLP.The resistance of 337 Yangtze-Huai soybean breeding line population(YHSBLP)to three P.sojae HeN08-35(3a,3c,4,5,6,7),AH(2,3a,3b,4,5),PNJ1(1d,2,3b,3c.4,5,7),were studied using hypocotyl inoculation method,the results showed 172 resources were resistant to one P.sojae,62 resources were resistant to two P.sojae,and 68 elite resources were resistant to all three P.sojae and were used by developing resistance accession in soybean breeding.2.Genome-wide association mapping of resistance to Phytophthora sojae in YHSBLP.The RTM-GWAS software and Tassel software were used by genome-wide association mapping of resistance to three Phytophthora sojae.The resistance locus of Yangtze-Huai soybean breeding germplasm including 16633 SNPLDBs were dug using RTM-GWAS,the results showed that in total of 145 resistance loci were identified.Genome-wide association mapping of resistance to P.sojae was also carried out with 60,862 SNPs with Tassel software analysis.With population structure and kinship as covariates,adopting mixed linear model(MLM),26 SNP new markers are identified significantly Phytophthora resistance associations.The loci with high rate of explanation for phenotypic variation were located a same 441 kb region by two software on chromosome 1(Chr.01).According to Glyma1.0 database,three genes Glyma01g32800,Glyma01g32825and Glyma01g32855 in 441 kb region were acted as candidate gene by gene annotation and induced expression by qRT-PCR verification.3.Fine mapping of a resistance gene RpsHN that controls Phytophthora sojae and candidate gene analysis.Initial Mapping of the RpsHN Gene was finished with two recombinant inbred line(RIL)populations.In this study,a 159 F2:3 secondary population derived from a cross of Meng8206 × Linmeng6-46,were used to fine map this locus using SSR markers.Finally,the resistance locus from Meng8206 was fine mapped to a 278.7 kb genomic region flanked by SSR markers SSRSOYN-25 and SSRSOYN-44 at a genetic distance of 1.6 and 1.0 cM on chromosome 3(Chr.03).Real-time RT-PCR analysis of the possible candidate genes showed that three genes(Glyma03g04260,Glyma03g043009 and Glyma03g04340)are likely involved in PRR resistance.In this study,GmM8HNstpk,homologous gene of Glyma03g04340,was cloned from meng8206 and linmeng6-46.The full length of GmM8HNstpk cDNA is 1914 bp.This cDNA sequence encoded 637 amino acid residues with a predicted molecular mass of 159.5KD and isoelectric point of 4.94,one highly conserved serine-threonine kinase domain were contened in the putative encoded protein.