Importance of 2,4-DAPG in the biological control of brown patch by Pseudomonas fluorescens HP72 and newly identified genes involved in 2,4-DAPG biosynthesis
2004
He, Y. (Tokyo Univ. (Japan)) | Suzuki, S. | Aono, T. | Oyaizu, H.
The Pseudornonas fluorescens strain HP72 used as biocontrol agent was isolated from the roots of creeping bentgrass on brown patch-suppressive soil. This strain can suppress brown patch disease caused by Rhizoctonia solani. The analysis of secondary metabolites from strain HP72 revealed that it produced known antifungal compounds, 2,4-diacetylphlo-roglucinol (2,4-DAPG), HCN, and a fluorescent siderophore. In the present study, the Tn5-inserted mutants of strain HP72, which did not show any antifungal activity were selected. None of the mutants produced 2,4-DAPG but they produced a fluorescent siderophore, while some strains produced HCN. Therefore, it is suggested that 2,4-DAPG plays a major role in the biological control of brown patch disease caused by R. solani. In the genomic region where Tn5 was inserted, two open reading frames (ORFs A and B), which are not included in the 2,4-DAPG gene cluster of HP72, were detected. It was demonstrated that ORFs A and B are involved in the regulation of 2,4-DAPG biosynthesis.
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