1a.Objectives (from AD-416)
Verticillium wilt (VW) of potato is a widespread and persistent problem in virtually all significant production areas in the United States. The only successful control strategy currently available to growers is soil fumigation, which is expensive and environmentally harmful. Host plant resistance offers the most cost-effective long-term control strategy for VW. One likely candidate for a potato VW resistance (R) gene is an ortholog of the tomato Ve gene, which has been cloned and found to confer immunity to VW. We have recently developed a molecular marker within a Ve-like gene from resistant potato and found that this marker co-segregates with the VW resistance phenotype in a segregating population.
Our specific objectives are to:
1. Identify germplasm that has been previously documented to be either resistant or susceptible to VW and verify the resistance phenotype using quantitative PCR.
2. Amplify and sequence Ve orthologs from the resistant and susceptible individuals for use in identifying single nucleotide polymorphisms that differentiate resistant from susceptible Ve alleles.
1b.Approach (from AD-416)
Inoculations of seedlings from crosses between cultivated breeding parents, phenotypic characterization of the inoculated seedlings, stem DNA extraction and quantitative PCR.
This project is focused on further developing a molecular marker for resistance to verticillium wilt, a widespread problem for potato growers nationwide. Crosses have been made with parents that had been previously determined to possess resistance to Verticillium dahliae resulting in twenty-two families (4x). The parents included Dakota Trailblazer, Umatilla Russet, Russet Norkotah, and Ranger Russet. A real-time polymerase chain reaction (PCR) method has been developed to further define the Verticillium: potato interaction among potato cultivars and breeding genotypes. Real-time PCR clearly differentiated susceptible, moderately resistant and highly resistant cultivars. This real-time PCR method has been compared to traditional plating methods for pathogen quantification in potato stem tissue and was found to be highly correlated. The correlation between real-time PCR values and percent wilt also was strong. The project is monitored through phone calls and e-mail exchanges.