Development of Immuno Strip for Detection of Xanthomonas campestris pv. campestris the Causative Agent of Black Rot of Chinese Kale

Abstract

The immuno strip test kit for Xanthomonas campestris pv. campestris (Xcc), the causal agent of Chinese kale black rot disease, was developed to obtain convenient, rapid, highly efficient and accurate diagnostic tool for field application using serology and lateral flow technique. The polyclonal antibody specific to Xcc was produced by injecting purified membrane protein complex (MPC) into rabbit. The highest antibody titer of 1:128,000 was selected and then precipitated in saturated ammonium sulfate solution to produce pure immunoglobulin (IgG). IgG was subsequently labelled with Colloidal Gold (O.D. 0.5 at 540 nanometer) and respectively drawn on conjugated release pad. Goat anti rabbit (GAR) was used for the control line and the prepared IgG-Xcc was used for the test line on S&S-AE 99 nitrocellulose membrane. The test kit was then assembled and tested. Results showed that the immuno strip test kit developed was specific to Xcc the causative agent of black rot of Chinese kale. The sensitivity of the test kit was 104 cfu/ml, which was able to detect Xcc in 1:2,000 dilution plant sap within 10-15 mins.