Biological agents to control plant wilt

Abstract

© SGEM2019. Plant diseases are one of the central reasons causing serious problems of food security in the world, affecting the quality and quantity of crops. Recently more and more attention is paid to alternative eco-friendly methods of plant disease control. One of such methods is the use of special microorganisms (so called biological control agents, BCA) that exhibit antagonistic activity towards phytopathogens. Since many microbes, which are suppressive towards plant pathogens are present in the nature, it is important to find the most effective and universal ones for further use in agricultural routine. In the present study, suppressive activity of four potential BCA (Trichoderma asperellum, Pseudomonas putida PCL, Pseudomonas fluorescence WCS, Streptomyces sp.) was checked towards four plant pathogen strains isolated from wheat, tomato and potato plants. The pathogens causing root wilt of the plants were isolated and identified by means of 18S rRNA gene sequencing as Fusarium oxisporum, Fusarium oxisporum Hsol, Fusarium culmorum and Alternaria betae-kenyensis. The antagonistic activity of the BCA was checked using co-plating method on the LA media on the 7th day of incubation and expressed in percentage of plate area free from pathogen. It was revealed that both Pseudomonadaceae BCA were not antagonistically active to all the four plant pathogens. This result may be explained by the mechanisms that these bacteria use to suppress pathogens, which are indirect (competition or induction of plant systemic resistance) and specificity of the method used. As for Streptomyces sp. and T. asperellum, which express direct suppressiveness towards pathogens – antibiosis and prey-predatory mechanisms, correspondingly – different antagonistic effects were observed for all the four pathogens.