Xanthomonas citri infecting teak ( Tectona grandis ) in Brazil, characterization and copper resistance

Xanthomonas is a bacterial genus that comprises various plant pathogenic species responsible for losses in economically important crops. Between 2016 and 2018, several strains of Xanthomonas were isolated from teak seedlings, from two production sites, displaying bacterial leaf spot symptoms. Through BOX-PCR molecular marker, a clonal nature of these isolates was confirmed among the 26 isolates. Of those, two isolates, UnB-Xtec2D and UnB-XtecTg02(2), were sequenced and presented characteristics similar to other Xanthomonas . Average nucleotide identity identified all isolates as Xanthomonas citri. Multilocus Sequence analysis with a seven gene scheme and phylogenomic with non-recombinant SNPs sites showed teak isolates as closely related to pathovar fuscans and aurantifolii . Type 3 Secretion System Effectors had a unique profile for isolates originally from teak, also, identified recombination regions matched the position of 11 effectors. Host range studies with Phaseolus vulgaris (common bean), Corymbia citriodora (lemon-scented gum) , Vigna unguiculata (cowpea) , Eucalyptus urograndis (eucalypt) and Citrus latifolia (Tahiti lime) showed teak isolates as capable of causing symptoms on P. vulgaris and C. citriodora aside from teak . None of the isolates presented genes associated with copper resistance or could grow in copper-amended culture media. The probable origin of this Xanthomonas capable of infecting teak is distant from pv. melhusii , originally found in teak plants in India, with a likelihood of being another existing pathovar, as fuscans or aurantifolii which could have suffered a host jump or a new insertion within Brazil.