In the current study, an extensive investigation was carried out for evaluation of copper-resistant (CuR) strains of Xanthomonas citri subsp. citri (Xcc) in all citrus-growing regions of Iran. A total of 230 strains was obtained from symptomatic samples of Mexican lime and grapefruit in seven provinces. The strains were identified as Xcc pathotype A*. The present study is the most updated geographical distribution of the pathogen in Iran. Different sensitivity levels to copper were observed among strains. Some strains had the CuR phenotype. The CuR strains were restricted to two counties (Darab and Jahrom) of the Fars province. The resistant phenotypes of CuR strains were related to the copLAB genes, except for three strains that were PCR negative for copLAB and copABCD. There was variation in the size of the copB PCR amplicons in the strains analyzed. Three variant groups of copB were detected among the strains (variants П, V and VI). This is the first report which reveals the contribution of copB size of 1425 bp (variant П) to Xcc resistance to copper. According to our assays, X. euvesicatoria ICMP109 is clustered in the VI variant group. Furthermore, a new variant was identified based on copB features in Xcc A* strains from Singapore and Thailand. Phylogenetic analyses of copLAB sequences showed that two copper resistance genotypes of Xcc A* exist in Iranian strains. Better understanding of resistance to copper could help preventing the selection and spread of CuR strains to new regions or hosts plants.

在当前的研究中，对柑橘黄单胞菌亚种的抗铜（CuR）菌株进行了广泛的研究。citri (Xcc) 在伊朗所有柑橘种植区都有种植。从七个省的墨西哥酸橙和柚子的症状样本中总共获得了 230 株菌株。该菌株被鉴定为Xcc致病型A *。本研究是伊朗病原体地理分布的最新研究。不同菌株对铜的敏感性不同。一些菌株具有 CuR 表型。CuR 菌株仅限于法尔斯省的两个县（Darab 和 Jahrom）。除copLAB和copABCD PCR 阴性的 3 个菌株外，CuR 菌株的抗性表型与copLAB基因相关。分析的菌株中copB PCR 扩增子的大小存在差异。在菌株中检测到了三个copB变体组（变体 П、V 和 VI）。这是第一份揭示 1425 bp 大小的copB （变体 П）对 Xcc 铜抗性的贡献的报告。根据我们的检测，X. euvesicatoria ICMP109 聚集在 VI 变体组中。此外，根据来自新加坡和泰国的 Xcc A* 菌株中的copB特征，鉴定出了一种新的变体。copLAB序列的系统发育分析表明，伊朗菌株中存在两种 Xcc A* 铜抗性基因型。更好地了解铜抗性有助于防止 CuR 菌株选择并传播到新地区或宿主植物。