Detection Phenazine-1-carboxylic Acid Antibiotic in Fluorescent Pseudomonads of Wheat Rhizosphere and Its Effect on Biocontrol of Take-all Disease

Take-all disease caused by Gaeumannomyces graminis var.tritici(Ggt) is an important disease of wheat in Iran. For biolobical control of this disease,130 strains of Fluorescent Pseudomonads were isolated from rhizospheric soil of wheat in different regions of Khorasan province. Selection the more active strains was released, using dual culture test by Fluorescent Pseudomonads and Ggt on KB and PDA medium. Among them, 21 strains were selected as more active on Ggt showing the inhibited of mycelial growth at the rate of 11.25 up 51.25 %. The PCR technique was completed by using primers PCA2a and PCA3b for detection the gene responsible of Phenazine-1-carboxylic acid production. The result showed that 12 strains of 21 strains contain the Phenazine-1-carboxylic acid gene. The dark green pigmentation or crystalline deposits method was used for testing the expression of phenazine-1-carboxylic acid antibiotic. The results showed that 6 from 12 strains able to produce Phenazine-1-carboxylic acid. In greenhouse experiment the Phenazine-1-carboxylic acid positive strains showed higher ability of biocontrol on Take-all disease than other strains. This strains decreased disease severity at the rate of 77-80%. The comparable results were observed for fresh weight of root and aerial parts of plants. These results showed that Phenazine-1-carboxylic acid which produced by these strains has important role in reducing Take-all disease probably