Investigation of the Presence of Xylella fastidiosa: A Quarantine Pathogen in Potential Host Plants in Sri Lanka

Abstract

Xylella fastidiosa, a gram-negative, xylem-inhabiting devastating plant pathogenic bacterium is reported in around 600 host plant species. Xylella fastidiosa is a regulated-quarantine pathogen in the European Union where the confirmation of pathogen-free certification is required in international trade. At present, Taiwan is the only country in Asia with a long-term presence of this bacterium. Hence there may be a risk of introduction into Sri Lanka through international trade. Therefore, an investigation was conducted from December 2020 to March 2021 to find out the presence of X. fastidiosa in potential hosts in Sri Lanka. A total number of 54 composite samples were obtained from 23 potential host plant species declared in the regulation (EU) 2020/1201 of 14 August 2020 including ornamental plant species from nine districts where most of the export nurseries are scattered. These were tested for the presence of X. fastidiosa by PCR using specific primers targeting the conserved genomic region of the RNA polymerase sigma factor of the rpoD gene of 733 bp. The positive DNA was sourced from the French collection of Plant Associated Bacteria, CIRM-CFBP for comparison. All local samples were found to be free from X. fastidiosa. These preliminary investigation results are considered as an encouraging indication, considering that X. fastidiosa was not found in Sri Lanka, at least in the surveyed areas. However, frequent studies are needed to be conducted to monitor the pathogen invasion.