Abstract
This study deals with the potentiality of salicylic (SA) and benzoic (BA) acids for controlling the common blight of beans (CBB) caused by Xanthomonas axonopodis pv. phaseoli (Xap). Impacts of the application of SA and BA (1.2 mu g mL(-1)) on the plant biological parameters, bacterial count, disease severity, phenolic and salicylic acid contents as well as catalase activity in treated plants were investigated. In vitro, application of the both compounds at different concentrations (0.4, 0.8 and 1.2 mu g mL(-1)) significantly suppressed growth of the pathogen. Under greenhouse conditions, application of BA and SA considerably reduced the disease development by 81 and 71%, respectively after 4 days of the application as compared to infected control. After 12 days of BA application, plants were protected 49.2% from disease as compared with SA (44.6%). SA-treated plants showed significant increases in the SA content and total phenolic content. Also, BA-treated plants showed an increment in the total phenolic content. Bean plants treated with SA showed higher catalase activity than those treated with BA. In conclusion, this study supports the use of SA and BA as abiotic elicitors to protect bean plants from the common blight disease. This protection may be attributed to the resistance induction, activation of defense enzymes as well as augmentation the phenolic content and salicylic acid in the host cells.