Indole-3-acetic acid biosynthesis by Xanthomonas axonopodis pv. citri is increased in the presence of plant leaf extracts

Abstract Indole-3-acetic acid production by Xanthomonas strains pathogenic to citrus was analyzed by reversed-phase high-performance liquid chromatography, thin-layer chromatography, UV spectroscopy and gas chromatography-mass spectrometry, and quantified by high-performance liquid chromatography with fluorescence detection. Amounts of auxin produced by Xanthomonas strains were low when compared with indole-3-acetic acid biosynthesis by other bacteria. In three different experiments it was shown that the addition of plant leaf extracts to bacterial cultures increased indole-3-acetic acid biosynthesis by Xanthomonas axonopodis pv. citri 223.