Identification of the Bacterial Leaf Spot Pathogen of Poinsettia in China

Bacterial leaf spot of poinsettia has been first reported in China in 2003 and ascribed to Xanthomonas campestris pv. poinsettiicola following the traditional classification of xanthomonads. The present study was undertaken to elucidate the precise position of the causal bacterium in the newly proposed classification of xanthomonads, three bacterial isolates from China were compared with all known Xanthomonas type strains by a polyphasic approach including carbon source utilization profile, fatty acid methyl esters, analysis of 16S rRNA gene sequence and 16S–23S rDNA intergenic spacer sequences. The results indicated that these Chinese isolates could be further identified as a pathovar of Xanthomonas axonopodis.