Submitted to: International Congress on Pseudomonas Molecular Biology and Biotechnology
Publication Type: Proceedings
Publication Acceptance Date: 6/1/1997
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Pseudomonas aeruginosa PNA1, isolated from chickpea roots in India, inhibits mycelial growth of several root pathogens (Fusarium oxysporum, Fusarium udum, Rhizoctonia bataticola, Sclerotium rolfsii, and Pythium debaryanum) in culture. In Glucose-casaminoacid-yeast extract (GCY) medium, PNA1 produced two phenazine compounds, phenazine-1-carboxylic acid (PCA) in large amounts, and oxychlororaphine (OCP) in minor amounts. Two classes of Tn5 mutants with reduced capacity to inhibit Fusarium growth were analysed: prototrophs deficient for phenazine production, and tryptophan auxotrophs. One such tryptophan auxotroph, which had the Tn5 inserted in the trpC gene, did not produce phenazinesin GCY medium, and excreted anthranilate in the medium. This mutant retained however an antifungal activity against Pythium while the phenazine-negative mutants had lost completely their antagonism against all fungi tested. Pure anthranilate was also found to restrict the growth of Pythium in vitro and to protect tomato and salad seedlings from Pythium-induced damping-off.