Quantification of Ulocladium atrum in necrotic plant tissues by monoclonalantibody-based enzyme-linked immunosorbent assay

Five murine hybridoma cell lines secreting monoclonal antibodies (MAbs) wit h similar binding specificities were raised to extracts from cyclamen leave s colonized with Ulocladium atrum, a saprotrophic fungus used for biologica l control of Botrytis cinerea. One of the cell lines produced a MAb, UA-PC3 , which was used to develop a quantitative ELISA to determine the biomass o f U. al rum in extracts from colonized leaves. The antigen, which is water soluble, was present on the surface of conidia and hyphae and was secreted into culture fluids. Production of the antigen was much greater in vivo tha n in vitro. Germination of conidia took place in saline buffers at 4 degree sC after 6 h. To avoid amplification of the antigen in biomass assays of th e fungus in extracts from sporulating tissues, coating of microlitre wells in ELISA was reduced to 1 h.