BackgroundThere has been limited exploration ofcopLABgenotypes and associated copper resistance phenotypes inXanthomonasspp. in the southern Caribbean region. An earlier study highlighted a variantcopLABgene cluster found in one TrinidadianXanthomonas campestrispv.campestris(Xcc) strain (BrA1), with <90% similarity to previously reportedXanthomonas copLABgenes. With only one report describing this copper resistance genotype, the current study investigated the distribution of the BrA1 variantcopLABgene cluster and previously reported forms of copper resistance genes in localXanthomonasspp.MethodsXanthomonasspp. were isolated from black-rot infected lesions on leaf tissue from crucifer crops at intensively farmed sites with high agrochemical usage in Trinidad. The identity of morphologically identified isolates were confirmed using a paired primer PCR based screen and 16s rRNA partial gene sequencing. MGY agar amended with CuSO4.5H2O up to 2.4 mM was used to establish MIC’s for confirmed isolates and group strains as sensitive, tolerant, or resistant to copper. Separate primer pairs targeting the BrA1 variantcopLABgenes and those predicted to target multiple homologs found inXanthomonasandStenotrophomonasspp. were used to screen copper resistant isolates. Select amplicons were sanger sequenced and evolutionary relationships inferred from global reference sequences using a ML approach.ResultsOnly four copper sensitive/tolerantXanthomonassp. strains were isolated, with 35 others classed as copper-resistant from a total population of 45 isolates. PCR detection ofcopLABgenes revealed two PCR negative copper-resistant resistant strains. VariantcopLABgenes were only found in Xcc from the original source location of the BrA1 strain, Aranguez. Other copper-resistant strains contained othercopLABhomologs that clustered into three distinct clades. These groups were more similar to genes fromX. perforansplasmids andStenotrophomonasspp. chromosomal homologs than reference Xcc sequences. This study highlights the localisation of the BrA1 variantcopLABgenes to one agricultural community and the presence of three distinctcopLABgene groupings in Xcc and relatedXanthomonasspp. with defined CuSO4.5H2O MIC. Further characterisation of these gene groups and copper resistance gene exchange dynamics on and within leaf tissue between Xcc and otherXanthomonasspecies are needed as similar gene clusters showed variable copper sensitivity profiles. This work will serve as a baseline for copper resistance gene characterisation in Trinidad and the wider Caribbean region and can be used to boost already lacking resistant phytopathogen management in the region.