Use of ELISA to rapidly screen hazelnut for resistance to eastern filbert blight

A rapid and accurate screening system was developed to more rapidly identify resistance to eastern filbert blight based on an indirect enzyme-linked immunosorbent assay (ELISA) of greenhouse-inoculated hazelnut. Polyclonal antibodies were obtained from rabbits following immunization with antigens from pure cultures of Anisogramma anomala, the pathogen. One-thousand-fold dilution of the antiserum produced positive reactions to 1.7 x 10(5) dilutions of A. anomala-infected hazelnut tissue extracts, but did not react to 1.7 x 10(2) dilutions of healthy hazelnut tissue extracts. Symptomless plants infected by A. anomala were detected by the indirect ELISA 3 to 5 months after inoculation, an improvement over the 13- to 27-month incubation period required for susceptible genotypes to develop external symptoms of infection (cankers). ELISA was more sensitive and efficient than conventional microscopic assays (i.e., visualizing A. anomala mycelium in hand-sectioned plant tissue) in both healthy and infected extracts. The screening system was tested on selected progenies from populations segregating for a single, dominant resistance gene. ELISA detected 100% of the infections while microscopic examination detected only 36% of the infected samples. ELISA rapidly and reliably identifies hazelnut progeny with a gene conferring a high level of resistance derived from the cv. Gasaway.