Growth inhibition, bacteriostatic and bactericidal potential of four Iranian lichen species against some plant pathogenic bacteria

Plant diseases are one of the main limitations in crop production which impose annually great losses. Threatens and hazards resulted from ample and repetitive application of chemical pesticides against plant diseases tended to pay attention to natural, safe and environment-friendly products. Lichens due to possessing of great antimicrobial substances has been considered as one of the best sources for natural alternative products. In this research study, growth inhibition, bacteriostatic and bactericidal potential of methanol extract of five lichens including Pleopsidium gobiensis, Parmelina tiliacea, Anaptychia setifera and Lecanora argopholis obtained from Arasbaran, East Azarbaijan province of Iran on some plant pathogenic bacteria such as Pectobacterium atrosepticum, Pseudomonas syringae pv. syringae, Xanthomonas arboricola pv. juglandis and Rhizobium tumefaciens were studied using disc diffusion, minimal inhibitory and bactericide concentration methods. All lichen methanol extracts were bacteriostatic and bactericide on the above-mentioned bacteria. However, R. tumefaciens was the lowest senility to these extracts. Methanol extract of P. gobiensis was as inhibitive as streptomycin on P. syringae pv. syringae growth. In additionm, P. atrosepticum and X. arboricola pv. juglandis were highly sensitive to lichen extracts and streptomycin. The most bactericidal extracts was related to P. gobiensis on P. atrocepticum and P. tiliacea on X. arboricola pv. juglandis. Considering the results, it is suggested that lichen extracts may have remarkable potential in plant pathogenic bacteria and more investigations are required in the future studies.