NIKNEJAD KAZEMPOUR M., ANVARY M.F
Abstract
Bakanae disease caused by Fusarium moniliforme is important on rice. Pseudomonas fluorescens produces a
broad-spectrum antibiotic phenazine-carboxylic acid (PCA), which is causal agent of collar and root rot active
against a variety of fungal root pathogens. In this study the contaminated rice samples were collected from infected
farms of Guilan. Moreover 238 bacteria were isolated from rhizosphere. The antagonistic ability of 12 of them was
demonstrated with two culture methods. According to biochemical and culturing trial results, 8 isolates were identified
as Pseudomonas fluorescens. The effects of volatile HCN compounds produced by antagonisti P. fluorescens was found that
all isolates, inhibited growth of F. moniliforme in vitro. Culture filtrate and antibiotics from these isolates inhibited
growth of the pathogen. The two genes from seven gene locus of phenazine were clonek in E. coli DH5?. The DNA of all
isolates were extracted by CTAB method and phenazine C and D genes were cloned in E. coli DH5? by standard methods.
The successful cloning was confirmed by the blue/white screening results and recombinant plasmid agarose gel
electrophoresis. These results suggest that the P. fluorescens that produce PCA might play an important role
in the natural suppressiveness of these soil to causal agent of collar and root rot of rice.
Key words:
Bakanae disease, phenazine-carboxylic acid, gene cloning, rice, Fusarium moniliforme, Pseudomonas fluorescens