ABSTRACT
Vascular colonization by Verticillium dahliae of 14 potato (Solanum tuberosum) cultivars was evaluated in field trials by a culture plate method and an indirect competitive enzyme-linked immunosorbent assay (IC-ELISA). Whereas the culture plate technique quantifies fungal propa-gules, the monoclonal antibody-based immunoassay detects the soluble antigen, providing an indicator of fungal biomass. Differences in vascular colonization were evident with both methods; thus, cultivars could be ranked as susceptible, intermediate, or resistant. Linear regression analysis of means of each cultivar showed correlation coefficients (r2) ranging from -0.606 to -0.835. Spearman's rank correlation coefficient (rs) ranged from -0.65 to -0.91. Estimation by IC-ELISA of vascular colonization by V. dahliae in potato is as accurate as that by the culture plate technique, and results can be obtained in 3 days with an approximately 50% reduction in costs of materials and reagents. This quantitative immunoassay can be applied in potato breeding programs to evaluate resistance to Verticillium wilt.
