Serological Detection of Ralstonia solanacearum in Potatoes by ELISA and Immunofluorescence, and Comparison to PCR

Abstract

Bacterial wilt, caused by Ralstonia solanacearum, is a devastating disease that is widely distributed in tropical and subtropical areas of the world (6). The host range of this bacterium is extensive and includes plants of economic importance as well as many weed species (11). R. solanacearum has been divided into five biovars and into five races (5,7), but there is little correlation between the biovars and races except for race 3 and biovar 2. This group of organisms are responsible for Brown rot, a disease of disastrous economic effect, which is present in many potato producing areas in the world. R. solanacearum is a quarantine organism in many countries of the world but this pathogen is still reported to be spreading in latently infected planting material to new locations (6). In order to monitor the occurrence of R. solanacearum in potato tubers there is need for rapid and specific diagnostic tests with sufficient sensitivity to detect latent pathogen population in the tubers. Serological tests such as ELISA and Immunofluorescence using polyclonal and monoclonal antibodies to this bacterium were shown to be non-specific (9). Tests using molecular techniques such as PCR and hybridization have been developed for the detection of R. solanacearum (1,10) but these methods though sensitive and specific requires a certain amount of expertise and are costly. In this study an attempt was made to develop monoclonal antibodies to R. solanacearum which has good specificity and sensitivity.