Pathogen virulence factors as a basis for development methods and strategies to control plant disease on the example of fire blight on apple trees (review)

   Relevance. The analysis of domestic and foreign literature has demonstrated the wide distribution and harmfulness of Erwinia amylovora (Burrill.) Winslow et al., the causative agent of fire blight of fruit crops, including apple trees. The disease causes significant damage to agricultural production.

   Results. To date, the disease has been identified in more than 50 countries worldwide. The pathogen affects about 200 species of the Rosaceae family, causing drying out of individual organs followed by death of the entire plant. The high level of virulence of the bacterium is provided by a number of physiological features. E. amylovora is equipped with a secretion system of type III effector proteins, which allows it to deliver them directly to the host cell. Also, the production of exopolysaccharides, lipopolysaccharides, cell motility and other properties help the bacterium to colonize host plants. The ability to control these virulence factors will reduce the ability of the bacterium to cause fire blight on fruit crops. From this point of view, disease control methods based on creating conditions for incompatible interactions between the host plant and the pathogen are promising. This approach is based on an in-depth understanding of the mechanism of E. amylovora pathogenesis. In this regard, information is needed on the virulence factors of the bacterium and the features of the plant immune response responsible for establishing the relationship between the parasite and the host.

   Conclusion. This review contains material on a number of areas related to the causative agent of fire blight of fruit crops E. amylovora. The issues of the geographical distribution of the bacterium are covered; the range of host plants is determined; the biological characteristics of E. amylovora are given; the symptoms of the disease it causes are described; virulence factors that are most significant for ensuring plant protection from the disease under study are identified. Theoretical and practical achievements in the field of genetics, molecular biology, plant physiology, and microbiology are considered, which are of great importance for the integration of modern biotechnologies in order to increase the effectiveness of fight against fire blight of fruit crops.

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