copLAB gene prevalence and diversity among Trinidadian Xanthomonas spp. black-rot lesion isolates with variable copper resistance profiles.

Only four copper sensitive/tolerant sp. strains were isolated, with 35 others classed as copper-resistant from a total population of 45 isolates. PCR detection of genes revealed two PCR negative copper-resistant resistant strains. Variant genes were only found in Xcc from the original source location of the BrA1 strain, Aranguez. Other copper-resistant strains contained other homologs that clustered into three distinct clades. These groups were more similar to genes from plasmids and spp. chromosomal homologs than reference Xcc sequences. This study highlights the localisation of the BrA1 variant genes to one agricultural community and the presence of three distinct gene groupings in Xcc and related spp. with defined CuSO.5HO MIC. Further characterisation of these gene groups and copper resistance gene exchange dynamics on and within leaf tissue between Xcc and other species 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.