The causative agent of basal bacteriosis in wheat agrophytocenosis

Abstract

Purpose. To identify the causative agent of basal bacteriosis of wheat Pseudomonas syringae pv. atrofaciens on host plant and segetal flora in wheat agrophytocenosis under intensive and organic systems of cultivation and to determine its harmfulness. Methods. Isolation of Pseudomonas syringae pv. atrofaciens (McCulloch 1920) Young, Dye & Wilkie 1978 from wheat and segetal plants in wheat crops was carried out in three regions of Ukraine (Kyiv, Poltava and Chernihiv). To study the properties of the bacteria, morphological, cultural, physiological, biochemical, serological, and molecular biological methods were used. Antigenic properties of the P. syringae bacterial strains were studied with agglutination and precipitation reactions, and pathogenic properties were studied by artificially infecting wheat plants during booting phase. Determination of heterogeneity in population of basal bacteriosis pathogen and identification of bacteria was carried out using RAPD-PCR and electrophoresis of the bacteria outer membrane proteins. Results. In all the fields surveyed in Kyiv, Poltava, and Chernihiv regions of Ukraine, wheat plants with lesions characteristic of basal bacteriosis were found. By pathogenic, morphological, cultural, physiological and biochemical properties, isolates from wheat plants were identified as P. syringae pv. atrofaciens. Isolated from affected wheat plants strains of P. syringae pv. atrofaciens were virulent, 80 % of isolates were characterized by high and medium aggressiveness towards the host plant. From the weeds in wheat crops virulent bacteria for the host plant and wheat were isolated, which by morphological, physiological, and biochemical characteristics belong to the species P. syringae. According to the serological properties, RAPD-PCR analysis with the OPA-13 primer and SDS-PAAG of protein profiles, it can be stated that the strains we isolated from weeds affected with bacterioses in wheat agrophytocenosis belong to P. syringae pv. atrofaciens. Conclusions. P. syringae pv. atrofaciens is the dominant pathogen of wheat basal bacteriosis in Ukraine which affects this crop in both the intensive and the organic crop management system. For the first time, from weeds grown in wheat crops there were isolated virulent for the host plants and the wheat plants bacteria P. syringae pv. atrofaciens.