Bacteria Pseudomonas sp. and Pantoea sp. Are the New Etiological Agents of Diseases on Forest Trees

Forest trees significantly affect human life. The spread of pathogens, including bacterial ones, poses a serious threat to their health. Despite this, however, the species composition and distribution of pathogenic bacteria, as well as the etiology of common diseases affecting forest trees, remain virtually unstudied. In this study, we, for the first time, describe different species of Pseudomonas and Pantoea as new etiological agents associated with the symptoms of leaf spotting and wood darkening on Acer tataricum L., Fraxinus pennsylvanica L., Ulmus minor Mill. Ulmus laevis Pallas. and Populus tremula L. For the identification of bacteria species, we used an integrated approach based on the characterization of their morphology, biochemistry, physiology and genetics. Phylogenetic analysis was performed using multilocus typing for five genes for Pseudomonas and six genes for Pantoea. Leaf spotting on A. tataricum, F. pennsylvanica, U. minor and U. laevis was shown to be caused by Pseudomonas cerasi, Pseudomonas congelans, Pseudomonas graminis, Pseudomonas syringae and Pantoea agglomerans both in monoinfection and coinfection. Wood darkening in U. minor U. laevis and P. tremula was found to be associated with the presence of Pantoea sp. and P. agglomerans. The coinfection of forest trees with bacteria of the genera Pseudomonas and Pantoea indicates a complex mechanism of interaction between the two populations, which will be the subject of future studies.