Identification and molecular mapping of Rps11, a novel gene conferring resistance to Phytophthora sojae in soybean.

Rps11 confers excellent resistance to predominant Phytophthora sojae isolates capable of defeating major Rps genes deployed into soybean production, representing a novel source of resistance for soybean cultivar enhancement. Phytophthora root and stem rot (PRSR), caused by the soil-borne pathogen Phytophthora sojae, is a devastating disease of soybean [Glycine max (L.) Merr.] throughout the world. Deploying resistant soybean cultivars is the most effective and environmentally friendly approach to managing this disease. The soybean landrace PI 594527 was found to carry excellent resistance to all P. sojae isolates examined, some of which were capable of overcoming the major Rps genesp, such as Rps1-k, Rps1-c, and Rps3-a, predominantly used for soybean protection in the past decades. A mapping population consisting of 58 F2 individuals and 209 F2:3 families derived from a cross between PI 594527 and the susceptible cultivar 'Williams' was used to characterize the inheritance pattern of the resistance to P. soja (Rps) in PI 594527. It was found that the resistance was conferred by a single Rps gene, designated Rps11, which was initially defined as an ~5 Mb genomic region at the beginning of chromosome 7 by bulked segregant analysis (BSA) with a nucleotide polymorphism (SNP) chip comprising 7039 SNP markers. Subsequently, simple sequence repeat (SSR) markers in the defined region were used to genotype the F2:3 mapping population to map Rps11 to a 225.3 kb genomic region flanked by SSR markers BARCSOYSSR_07_0286 and BARCSOYSSR_07_0300, according to the soybean reference genome sequence. Particularly, an SSR marker (i.e., BARCSOYSSR_07_0295) was found to tightly co-segregate with Rps11 in the mapping population and can be effectively used for marker-assisted selection of this gene for development of resistant soybean cultivars.

Ping J ，Fitzgerald JC ，Zhang C ，Lin F ，Bai Y ，Wang D ，Aggarwal R ，Rehman M ，Crasta O ，Ma J ... -  《-》

Molecular mapping of two genes conferring resistance to Phytophthora sojae in a soybean landrace PI 567139B.

Phytophthora root and stem rot (PRR), caused by the soil-borne oomycete pathogen Phytophthora sojae, is one of the most destructive diseases of soybean. PRR can be effectively controlled by race-specific genes conferring resistance to P. sojae (Rps). However, the Rps genes are usually non-durable, as populations of P. sojae are highly diverse and quick to adapt, and can be overcome 8-15 years after deployment. Thus, it is important to identify novel Rps genes for development of resistant soybean cultivars. PI 567139B is a soybean landrace carrying excellent resistance to nearly all predominant P. sojae races in Indiana. A mapping population consisting of 245 F2 individuals and 403 F2:3 families was developed from a cross between PI 567139B and the susceptible cultivar 'Williams', and used to dissect the resistance carried by PI 567139B. We found that the resistance in PI 567139B was conferred by two independent Rps genes, designated RpsUN1 and RpsUN2. The former was mapped to a 6.5 cM region between SSR markers Satt159 and BARCSOYSSR_03_0250 that spans the Rps1 locus on chromosome 3, while the latter was mapped to a 3.0 cM region between BARCSOYSSR_16_1275 and Sat_144, approximately 3.0-3.4 cM upstream of Rps2 on chromosome 16. According to the 'Williams 82' reference genome sequence, both regions are highly enriched with NBS-LRR genes. Marker assisted resistance spectrum analyses of these genes with 16 isolates of P. sojae, in combination with the mapping results, suggested that RpsUN1 was likely to be a novel allele at the Rps1 locus, while RpsUN2 was more likely to be a novel Rps gene.

Lin F ，Zhao M ，Ping J ，Johnson A ，Zhang B ，Abney TS ，Hughes TJ ，Ma J ... -  《-》

Genetic analysis and fine mapping of RpsJS, a novel resistance gene to Phytophthora sojae in soybean [Glycine max (L.) Merr].

We finely map a novel resistance gene ( RpsJS ) to Phytophthora sojae in soybean. RpsJS was mapped in 138.9 kb region, including three NBS-LRR type predicted genes, on chromosome 18. Phytophthora root rot (PRR) caused by Phytophthora sojae (P. sojae) has been reported in most soybean-growing regions throughout the world. Development of PRR resistance varieties is the most economical and environmentally safe method for controlling this disease. Chinese soybean line Nannong 10-1 is resistant to many P. sojae isolates, and shows different reaction types to P. sojae isolates as compared with those with known Rps (Resistance to P. sojae) genes, which suggests that the line may carry novel Rps genes or alleles. A mapping population of 231 F(2) individuals from the cross of Nannong 10-1 (Resistant, R) and 06-070583 (Susceptible, S) was used to map the Rps gene. The segregation fits a ratio of 3R:1S within F(2) plants, indicating that resistance in Nannong 10-1 is controlled by a single dominant gene (designated as RpsJS). The results showed that RpsJS was mapped on soybean chromosome 18 (molecular linkage group G, MLG G) flanked by SSR (simple repeat sequences) markers BARCSOYSSR_18_1859 and SSRG60752K at a distance of 0.9 and 0.4 cm, respectively. Among the 14 genes annotated in this 138.9 kb region between the two markers, three genes (Glyma18g51930, Glyma18g51950 and Glyma18g51960) are the nucleotide-binding site and a leucine-rich repeat (NBS-LRR) type gene, which may be involved in recognizing the presence of pathogens and ultimately conferring resistance. Based on marker-assisted resistance spectrum analyses of RpsJS and the mapping results, we inferred that RpsJS was a novel gene or a new allele at the Rps4, Rps5 or Rps6 loci.

Sun J ，Li L ，Zhao J ，Huang J ，Yan Q ，Xing H ，Guo N ... -  《-》

Identification and molecular mapping of Rps14, a gene conferring broad-spectrum resistance to Phytophthora sojae in soybean.

A soybean landrace carries broad-spectrum resistance to Phytophthora sojae, which is conferred by a single gene, designated Rps14, on the short arm of chromosome 3. Phytophthora sojae is the causative agent for Phytophthora root and stem rot in soybean [Glycine max (L.) Merr.] and can be managed by deployment of resistance to P. sojae (Rps) genes. PI 340,029 is a soybean landrace carrying broad-spectrum resistance to the pathogen. Analysis of an F population derived from a cross between PI 340,029 and a susceptible cultivar 'Williams' reveals that the resistance to P. sojae race 1 is conferred by a single gene, designated Rps14, which was initially mapped to a 4.5-cM region on the short arm of chromosome 3 by bulked segregant analysis (BSA), and subsequently narrowed to a 1.48 cM region corresponding to 229-kb in the Williams 82 reference genome (Wm82 v2.a1), using F families derived from the F population. Further analysis indicates that the broad-spectrum resistance carried by PI 340,029 is fully attributable to Rps14. The genomic sequences corresponding to the defined Rps14 region from a set of diverse soybean varieties exhibit drastic NBS-LRR gene copy number variation, ranging from 3 to 17 copies. Ultimate isolation of Rps14 would be critical for precise selection and deployment of the gene for soybean protection.

Chen L ，Wang W ，Ping J ，Fitzgerald JC ，Cai G ，Clark CB ，Aggarwal R ，Ma J ... -  《-》

A Novel Phytophthora sojae Resistance Rps12 Gene Mapped to a Genomic Region That Contains Several Rps Genes.

Phytophthora sojae Kaufmann and Gerdemann, which causes Phytophthora root rot, is a widespread pathogen that limits soybean production worldwide. Development of Phytophthora resistant cultivars carrying Phytophthora resistance Rps genes is a cost-effective approach in controlling this disease. For this mapping study of a novel Rps gene, 290 recombinant inbred lines (RILs) (F7 families) were developed by crossing the P. sojae resistant cultivar PI399036 with the P. sojae susceptible AR2 line, and were phenotyped for responses to a mixture of three P. sojae isolates that overcome most of the known Rps genes. Of these 290 RILs, 130 were homozygous resistant, 12 heterzygous and segregating for Phytophthora resistance, and 148 were recessive homozygous and susceptible. From this population, 59 RILs homozygous for Phytophthora sojae resistance and 61 susceptible to a mixture of P. sojae isolates R17 and Val12-11 or P7074 that overcome resistance encoded by known Rps genes mapped to Chromosome 18 were selected for mapping novel Rps gene. A single gene accounted for the 1:1 segregation of resistance and susceptibility among the RILs. The gene encoding the Phytophthora resistance mapped to a 5.8 cM interval between the SSR markers BARCSOYSSR_18_1840 and Sat_064 located in the lower arm of Chromosome 18. The gene is mapped 2.2 cM proximal to the NBSRps4/6-like sequence that was reported to co-segregate with the Phytophthora resistance genes Rps4 and Rps6. The gene is mapped to a highly recombinogenic, gene-rich genomic region carrying several nucleotide binding site-leucine rich repeat (NBS-LRR)-like genes. We named this novel gene as Rps12, which is expected to be an invaluable resource in breeding soybeans for Phytophthora resistance.

Sahoo DK ，Abeysekara NS ，Cianzio SR ，Robertson AE ，Bhattacharyya MK ... -  《PLoS One》