Detection and quantification of Botrytis cinerea by ELISA in pear stems during cold storage

Botrytis cinerea was detected and quantified in pear stems from six orchard s in the Pacific Northwest, and changes in fungal biomass in the stems afte r 6 and 8 months of cold storage in regular (air) atmosphere were studied. The fungus was detected by plating stem halves on selective medium and by e nzyme-linked immunosorbent assay (ELISA) using the Botrytis-specific monocl onal antibody BC-12.CA4. Both methods demonstrated that the incidence of B. cinerea increased from 6 to 8 months, but ELISA was more sensitive than st andard isolation. Quantitative ELISAs on stems indicated that over 200 mu g of B. cinerea biomass per gram of stem tissue was present in the stems of visibly rotted fruits, but usually less than 35 mu g/g was present in stems from fruits without visible gray mold. Aureobasidium pullulans, Penicilliu m spp., Alternaria spp., and Cladosporium spp. were commonly isolated from stem tissue. A. pullulans was present in 86% of the stems from which B. cin erea was detected. Use of the monoclonal antibody BC-12.CA4 could help in d etermining the infection path of B. cinerea in pear stems and detection of latent infections, enabling the timing and method of control of stem end ro t to be optimized.