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Kosakoniacowanii as the New Bacterial Pathogen Affecting Soybean (Glycine max Willd.)

Krzysztof Krawczyk, Natasza Borodynko-Filas
European journal of plant pathology 2020 v.157 no.1 pp. 173-183
Glycine max, Pseudomonas syringae, Xanthomonas axonopodis pv. glycines, bacteria, blight, crops, endophytes, hosts, humans, leaves, new host records, niches, pathogenicity, plant pathogens, polymerase chain reaction, ribosomal DNA, screening, secondary infection, sequence analysis, soybeans, virulent strains, Poland
Soybean (Glycine max Willd.) is one of the most economically important crops in the world, and it’s importance continuously increasing. Routine screening of Polish soybean fields has revealed an outburst of a new disease of soybean plants, with symptoms resembling those described for the bacterial blight, caused by Pseudomonas syringae pv. glycinae, and bacterial pustule caused by Xanthomonas axonopodis pv. glycines. The symptoms were observed in the field, on the leaves of investigated plants. The goal of this paper was the identification and characterization of the causal agent of that disease. Our studies have excluded virus and fungi and pointed the bacteria as the disease causal agent. Identification based on biological (Biolog Gen III), and molecular methods (16S rDNA, and gyrB sequencing, PCR species-specific testing) revealed that the soy pathogenic bacteria is Kosakonia cowanii species. We believe that the presence of such pathogens in the environment pose a serious threat for the crops and is also a warning, that in the near future we may be faced a new type of bacterial pathogens: both epi- and endophytic, abundant in the natural environment, with huge metabolic potential, and ability of quick colonization of new ecological niches and hosts, e.g. opportunistic pathogens of plants or humans. What’s important is that the plant-pathogenic and plant-epiphytic “environmental” strains of such species can be distinguished from each other only post factum, in the pathogenicity tests. They are indistinguishable or very hard to distinguish morphologically, biochemically or molecularly.