CO2 Assimilation of Bean Plants (Phaseolus vulgaris L.) in Response to Defense Activators to Xanthomonas axonopodis pv. Phaseoli and its Variant Fuscans

Abstract

Common bacterial blight is one of the most important diseases in bean crop. Currently, the use of beneficial microorganisms to protect agricultural crops is booming, however, the control efficiency achieved with its application is even lower than conventional methods, which suggests more studies to understand the site and mechanism of protection. The present work was carried out with the purpose of evaluating the effect of the phytohormones jasmonic and salicylic acid, and of the beneficial microorganisms Trichoderma asperellum and Bacillus pumilus as foliar treatments for the protection against the bacterial common blight disease in bean plants. The phytopathogenic bacteria that cause this disease were isolated and identified through biochemical tests. The effect of these bacteria and the treatments on the assimilation of CO 2 , stomatal conductance and opening of bean plants were evaluated. Isolation of the bacteria Xanthomonas axonopodis pv. phaseoli(Xap) and Xanthomonas axonopodis pv. phaseoli var. fuscans(Xapf) was achieved. The analysis of variance of the evaluated variables indicated a significant difference due to the effect of phytopathogenic bacteria and treatments. The plants inoculated with the Xapf bacteria showed greater severity of the disease. The plants treated with jasmonic acid presented higher tolerance to the causal agents with respect to the rest of the treatments and reduced the assimilation of CO 2 . No statistically significant difference was found between the rest of the treatments and the control.