Background Xanthomonas spp. causes bacterial spot disease, which reduces quality and yield of pepper crops in Mexico. Identification of phytopathogen species is necessary to implement more effective control strategies. Objective The aim of this study was to isolate and identify infecting Xanthomonas species in South Central Chihuahua pepper-producing areas. Methods Diseased plants were collected from 30 cultivation lots and bacteria were isolated from damaged tissues. Potential causative agents were isolated, identified, and characterized by biochemical and molecular analysis. Pathogenicity tests from each isolate were then performed on 30-d-old pepper seedlings, exposing five leaves to 10 µL of 1 × 108 CFU/mL bacterial suspensions of each isolate, using sterile distilled water as a control. Disease severity was determined after 10 d by calculating leaf damage percentage. Furthermore, we evaluated the susceptibility of the highest bacterial spot severity-causing isolates (13 isolates) to copper sulphate (CuS), copper gluconate (CuG), copper oxychloride + oxytetracycline hydrochloride (Cu + Ox), gentamicin + oxytetracycline hydrochloride (Gen + Ox), and gentamicin sulphate (GenS). Copper-resistance genes (copLAB) were detected by PCR analysis among isolates. Results Thirty-seven foliage isolates were identified as Xanthomonas euvesicatoria (14%), which were associated with bacterial spot disease in jalapeño pepper. Tested Xanthomonas isolates were resistant to Cu-based compounds, but susceptible to Cu + Ox. All isolates were susceptible to Gen + Ox and GenS. CopLAB genes were detected in all but one strain. Conclusions X. euvesicatoria (formally X. perforans) may be considered as an emerging pathogen of bacterial spot pepper in Mexico. Among disease management strategies, alternatives to copper should be taken into consideration.

中文翻译：

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墨西哥中南部奇瓦瓦州辣椒作物中与细菌性斑病严重程度相关的 euvesicatoria 黄单胞菌（正式为 X. perforans）的流行率

背景黄单胞菌属。导致细菌性斑点病，从而降低墨西哥辣椒作物的质量和产量。鉴定植物病原体物种对于实施更有效的控制策略是必要的。目的本研究的目的是分离和鉴定中南部奇瓦瓦辣椒产区的感染性黄单胞菌属。方法从30个栽培批次收集病株，从受损组织中分离细菌。通过生化和分子分析分离、鉴定和表征潜在的病原体。然后对 30 天龄的辣椒幼苗进行每种分离物的致病性测试，将五片叶子暴露于 10 μL 的每种分离物的 1 × 108 CFU/mL 细菌悬浮液中，使用无菌蒸馏水作为对照。10 d 后通过计算叶片损伤百分比确定疾病严重程度。此外，我们评估了引起细菌斑严重程度最高的分离物（13 个分离物）对硫酸铜 (CuS)、葡萄糖酸铜 (CuG)、氯氧化铜 + 盐酸土霉素 (Cu + Ox)、庆大霉素 + 盐酸土霉素 (Gen + Ox) 和硫酸庆大霉素 (GenS)。铜抗性基因 (copLAB) 通过 PCR 分析在分离株中进行检测。结果 37 株叶子分离株被鉴定为黄单胞菌（14%），它们与墨西哥胡椒的细菌性斑点病有关。测试的黄单胞菌分离物对基于铜的化合物具有抗性，但对 Cu + Ox 敏感。所有分离株都对 Gen + Ox 和 GenS 敏感。除一种菌株外，所有菌株均检测到 CopLAB 基因。结论十。euvesicatoria（正式名称为 X. perforans）可能被认为是墨西哥细菌斑点胡椒的一种新出现的病原体。在疾病管理策略中，应考虑铜的替代品。