Pasichnyk L. Phytopathogenic and saprophytic bacteria of wheat and oat agroecosystems

Dissertation is devoted the study of interactions between phytopathogenic and saprophytic bacteria (both epiphytic and endophytic) in vitro and in vivo, and to establish the mechanism of main cereal crops pathogens distribution based on wheat and oat analysis. The surface of host and immune plants is the ecological niche of saprotrophic existence of phytopathogens. The interactions between phytopathogenic and saprophytic bacteria is complex and multivector. Saprophytic bacteria of wheat are more competitive compared to phytopathogenic ones. Saprophytes reduce symptoms of development of disease and course of the infectious process caused by phytopathogenic bacteria. In turn, phytopathogens induce in P. agglomerans production of signaling molecules - acylhomoserinlactone. The capability of epiphytic isolates, so as endophytes, to colonize internal plant tissue was proved by molecular-genetic analysis of gusA-gene. The heterogeneity of biological properties of P. syringae natural and collection populations is established. Nevertheless, the bacterial living conditions in different econiches do not influence on fatty-acid composition of their lipids. It was shown that certain serogroups influence the bacterial adaptation to living conditions. The structure of O-polysaccharide (O-PS) chains of P. syringae pv. coronafaciens 9030 and P. syringae pv. atrofaciens 8281 was established. There are 3 types of O-chains. The main chain consists of L-rhamnose remains with 3-acetamido-3,6-dideoxy-D-galactose as side substituent. Lipopolysaccharides (LPS) of P. syringae pv. coronafaciens 9030 and P. syringae pv. atrofaciens 8281 possess antimutagenic (in the Ames test) and antitumor (against A. tumefaciens) properties. The exhibition of hypersensitive reaction on tobacco leaves is depended on P. syringae age, the day time of injection and salts of heavy metals. LPS of P. syringae does not influence on hypersensitive reaction.