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.
We have utilized quantitative polymerase chain reaction (PCR) to define the interaction between Verticillium and potato in populations derived from popular potato varieties. This method is successful in differentiating susceptible, moderately resistant, and highly resistant varieties. This method was compared to traditional plating methods for pathogen quantification with Pearson’s correlation revealing a strong relationship between these assays. The correlation between quantitative PCR values and percent wilt evaluated two weeks after stem sampling also was strong. The results indicate that this PCR assay can be utilized to detect V. dahliae in potato stems grown under field conditions and is able to quantify the pathogen in potato plants. The project is monitored through in person discussions, phone calls, and e-mail exchanges.