Molecular detection of exotic phytopathogenic bacteria: a case study involving canker-like symptoms on citrus

摘要

Early detection and accurate diagnoses of plant diseases are crucial if New Zealand's horticultural industries are to be protected from the destructive effects of new introductions of phytopathogenic bacteria. Citrus canker, caused by Xanthomonas axonopodis pv. citri (Xac), was eradicated from New Zealand in 1972 but continues to be a biosecurity threat to the citrus industry here. In this study we evaluated and adapted molecular diagnostic procedures for the detection of exotic phytopathogenic bacteria. These techniques were used to identify the bacteria isolated from the canker-like symptoms observed on citrus leaves in Kerikeri and allowed the elimination of Xac as the causal agent. Although the symptoms were similar to citrus canker, the causalagent was found to be Elsinoe fawcettii. The applications of the developed techniques for accurate identification of the pathogen on citrus are discussed.