The goal of this research is to develop elite soybean lines with improved resistance to Phytophthora sojae, the pathogen that causes Phytophthora root rot. In a previous ISA funded project mapping QTLs for partial resistance to P. sojae, we identified a potential novel gene for resistance to this pathogen. The goal of this proposal is to develop elite soybean lines with improved resistance to P. sojae, the causal organism of Phytophthora root rot.

The researchers identified the RpsN gene region is located on Chromosome 3 (MLG N). SNP markers flanking the gene region was identified but were not tightly linked. SSR markers are being explored to cover the gaps in the genome maps and for the identification of tightly linked markers suitable for Marker-assisted selection. Suitable lines are being selected for the backcross program and DNA was isolated for all RILs to be sequenced for the identification of SNP markers associated with the RpsN region.

1. Generate molecular markers linked to RpsN.
2. Backcross RpsN into elite soybean germplasm lines.
3. Identify candidate RpsN genes.

1. Generate molecular markers linked to RpsN.
2. Backcross RpsN into elite soybean germplasm lines.
3. Identify candidate RpsN genes.

Update:
The researchers report that two RIL populations were screened for resistance to P. sojae with P. sojae isolate R17 and combined R17 and Val12-11 isolates resulted in two genes and a single gene segregation, respectively; twelve polymorphic SSR markers have been identified in the parental lines were used to screen the populations, of which 3 were successfully mapped in one of the RIL populations; F2 seeds of AX20931 population received from Dr. Cianzio were advanced to the F3 generation in the greenhouse; and genetic maps were regenerated and the mapping was conducted using ICIMapping software.

• Screening of the two RIL populations with P. sojae isolate R17 (1b,1d,3a,3b,3c,5,6) and combined R17 and Val12-11 (1a,1b,1c,1d,1k,2,4,7) isolates resulted in 2 genes and a single gene segregation, respectively.
• Populations were screened with twelve polymorphic SSR markers identified in the parental lines and 3 were successfully mapped in one of the RIL populations.
• Genetic maps were regenerated and the mapping was conducted using ICIMapping software.
• F2 seeds of the AX20925 population are being screened to determine the gene action.
• DNA pools of the resistant and susceptible RIL are currently being sequenced.