First report of bacterial blight of Anthurium andreanum in Poland

In July 2007, symptoms of bacterial blight were observed on leaves of anthurium plants growing in a commercial greenhouse in central Poland. Disease incidence was approximately 10% at the time of inspection. Symptoms were manifested as water soaked lesions that turned dark brown with chlorotic margins, forming regular or round spots up to 2 cm diameter, most often at the leaf margins. Spathe infection was also observed. Diseased plants died quickly during the summer. From the margin of diseased tissue, yellow colony-forming bacteria were isolated on YPGA and King's B media. The isolates were identified as Xanthomonas axonopodis pv. dieffenbachiae by a classical immunofluorescence test (IF) using polyclonal antibodies (Prime Diagnostics, Xcd (1104) I-9831-01) Anonymous, 2004. Isolates were identified as Xanthomonas sp. by PCR (Maes, 1993). They were also tested positively by PCR using two primer pairs, PXad and NXad, specific for X. axonopodis pv. dieffenbachiae (Robène-Soustrade et al., 2006). Based on amplified fragment length polymorphism (AFLP) analysis (Ah-You et al., 2007), isolates were identified as X. axonopodis pv. dieffenbachiae group 9.4. They were identical to a widely distributed haplotype that was previously identified in several regions of the world, including the European Union. Pathogenicity of isolates was assayed on leaves of healthy anthurium plants, by infiltration with bacterial suspensions (1 x 10⁷ CFU/ml) on inoculation sites of about 1 cm diameter. Plants were incubated at 28°C under humidity of 60-80%. Water soaked spots around inoculation sites were observed after ten days. To fulfill Koch's postulates, bacteria were re-isolated from plant tissue showing disease symptoms and were identified as X. axonopodis pv. dieffenbachiae using PCR with NXad and PXad primers.

This is the first report of bacterial blight of anthurium in Poland caused by X. axonopodis pv. dieffenbachiae.