Highly sensitive detection of <i>Ralstonia solanacearum</i> in latently infected potato tubers by post‐enrichment enzyme‐linked immunosorbent assay on nitrocellulose membrane

Abstract

A post‐enrichment enzyme‐linked immunosorbent assay (ELISA) on nitrocellulose membrane (NCM‐ELISA) is described for the detection of Ralstonia solanacearum in latently infected potato tubers. The polyclonal antiserum specificity was significantly improved by adsorption with cross‐reacting bacteria. The detection efficiency after enrichment was compared with those of nucleic acid spot hybridization (NASH), double‐antibody‐sandwich immunoassay (DAS‐ELISA) and plating on modified Kelman's medium. After 48 h of incubation of the tuber extracts with modified SMSA broth at 30°C, sensitivities of post‐enrichment NCM‐ELISA, DAS‐ELISA and NASH were similar. As few as 10cells mL −1 were detected in either inoculated or naturally infected tuber extracts. Of 255 field samples, no cross‐reactivity of NCM‐ELISA was observed. Post‐enrichment NCM‐ELISA thus provides a reliable and sensitive low‐cost method that is rapid and easy to use, making it suitable for assessing susceptibility of breeding lines to bacterial wilt, ecological studies and seed quality control in developing countries.