Abstract
BackgroundXanthomonas 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.ObjectiveThe aim of this study was to isolate and identify infecting Xanthomonas species in South Central Chihuahua pepper-producing areas.MethodsDiseased 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.ResultsThirty-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.ConclusionsX. 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.
Highlights
Chili pepper crop (Capsicum annuum L.) production in Mexico is an important agricultural activity, because of its high profitability, demand, and consumption
Isolation and identification of the causative agent In the present study, we isolated 43 Xanthomonas spp. strains from chili pepper leaves with characteristic infection of bacterial spots
No amplification was observed for negative controls and other species-specific primer pairs did not amplify DNA, which confirmed that the isolates do not belong to X. vesicatoria or X. gardneri (Fig. S2)
Summary
Chili pepper crop (Capsicum annuum L.) production in Mexico is an important agricultural activity, because of its high profitability, demand, and consumption. In Mexico, pepper crop yield reaches up to 25.51 ton/ha Diseases such as bacterial spot reduce yield to up to 66%, which represents about $7,500 dollars loss per ha (SIAP, 2018; Sharma & Bhattarai, 2019). Potential bacterial spot causative agents include Xanthomonas euvesicatoria, X. gardneri, X. euvesicatoria (formally X. perforans), and X. vesicatoria (Jones et al, 2004). Xanthomonas spp. causes bacterial spot disease, which reduces quality and yield of pepper crops in Mexico. Objective: The aim of this study was to isolate and identify infecting Xanthomonas species in South Central Chihuahua pepper-producing areas. Results: Thirty-seven foliage isolates were identified as Xanthomonas euvesicatoria (14%), which were associated with bacterial spot disease in jalapeño pepper. Alternatives to copper should be taken into consideration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
