Abstract
Bakanae disease caused by Fusarium fujikuroi is an important diseases on rice.Pseudomonas fluorescens produces the broad-spectrum antibiotic phenazine-carboxylic acid (PCA), which is active against a variety of fungal root pathogens. In this study two genes from seven gene locus of phenazine were cloned inEscherichia coli DH5α. The contaminated rice samples were collected from infected farms of Guilan. 238 bacteria were isolated from the rhizosphere. The antagonistic ability of 12 of which, was demonstrated with dual culture method. From the biochemical and culture results, 8 isolated were identified as P.fluorescens. The two genes from seven gene locus of phenazine were cloned intoE. coli DH5α. We speculate that P. fluorescens that produce 2,4-diacetylphloroglucinol (Phl) play an important role in the natural suppressiveness of this soil to causal agent of collar and root rot of rice. Key words: Fusarium fujikuroi, phenazine carboxylic acid, gene cloning, antagonist bacteria.
Highlights
There is increasing interest in applying microorganisms to control soil-borne plant pathogens
Pseudomonas fluorescens produces the broad-spectrum antibiotic phenazine-carboxylic acid (PCA), which is active against a variety of fungal root pathogens
Other secondary metabolites produced by beneficial bacteria can function to prevent infection by pathogens by altering the environment and improving the bacterium's ability to compete with pathogens, by inhibiting the activity of pathogens, or by triggering host defenses (Bloemberg and Lugtenberg, 2001; Raaijmakers et al, 2002)
Summary
There is increasing interest in applying microorganisms to control soil-borne plant pathogens. Other secondary metabolites produced by beneficial bacteria can function to prevent infection by pathogens by altering the environment and improving the bacterium's ability to compete with pathogens, by inhibiting the activity of pathogens, or by triggering host defenses (Bloemberg and Lugtenberg, 2001; Raaijmakers et al, 2002). The antibiotics phenazine-1carboxylic acid (PCA) and 2,4-diacetylphloroglucinol (Phl) are major determinants of biological control of soil-borne plant pathogens by various strains of fluorescent Pseudomonas spp. One possible approach to improve biological control may be the application of combinations of biocontrol agents (Duffy and Weller, 1995).
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