Bogema, Daniel R.

We report the presence of the emerging plant pathogen ‘ Xanthomonas cannabis ’ in Australia through a comprehensive analysis of five historical isolates and all publicly available genomes of the species. Using comparative genomics, we characterized four isolates collected from Zinnia spp. and one from Cucurbita pepo . Our findings show that the Zinnia isolates form a distinct phylogroup with the pathotype strain of ‘ X. cannabis ’ pv. zinniae . This group possesses genes for the type 3 secretion system (T3SS) and effectors, a variety of genes unique within the species, and nine genomic islands associated with virulence and drug resistance. In contrast, the C. pepo isolate is genetically distinct and lacks the T3SS but contains its own genes unique within the species. Hypersensitivity response assays confirmed the pathogenic potential of all five isolates in black bean, eggplant, green bean, tomato, sunflower, zinnia and zucchini plants. These results highlight the genetic diversity and evolving threat of this pathogen in Australia, underscoring the critical need for ongoing biosecurity surveillance.

The draft genome sequence of a novel “ Candidatus Liberibacter” species detected in an unidentified species of Zanthoxylum (Rutaceae) collected in Bhutan is reported. The total length is 1,408,989 bp with 1,169 coding sequences in 96 contigs, a GC content of 37.3%, and 76 to 77% average nucleotide identity with several other “ Ca . Liberibacter” species.