Induced accumulation of tyramine, serotonin, and related amines in response to Bipolaris sorokiniana infection in barley

• Published in: Bioscience, biotechnology, and biochemistry Vol. 81; no. 6; pp. 1090 - 1098
• Main Authors: Ishihara, Atsushi, Kumeda, Rie, Hayashi, Noriko, Yagi, Yukari, Sakaguchi, Nanase, Kokubo, Yu, Ube, Naoki, Tebayashi, Shin-ichi, Ueno, Kotomi
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 03.06.2017; Oxford University Press
• Subjects: Antifungal Agents - immunology; Antifungal Agents - metabolism; Antifungal Agents - pharmacology; barley; Bipolaris sorokiniana; Chromatography, High Pressure Liquid; dimer; Hordeum - immunology; Hordeum - metabolism; Hordeum - microbiology; Hydrophobic and Hydrophilic Interactions; Indoles - immunology; Indoles - metabolism; Indoles - pharmacology; Oryza - immunology; Oryza - metabolism; Oryza - microbiology; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Immunity; Plant Leaves - immunology; Plant Leaves - metabolism; Plant Leaves - microbiology; Poaceae; Saccharomycetales - drug effects; Saccharomycetales - pathogenicity; Saccharomycetales - physiology; serotonin; Serotonin - biosynthesis; Serotonin - immunology; Serotonin - pharmacology; Sesquiterpenes - immunology; Sesquiterpenes - metabolism; Sesquiterpenes - pharmacology; Setaria Plant - immunology; Setaria Plant - metabolism; Setaria Plant - microbiology; Species Specificity; Spores, Fungal - drug effects; Spores, Fungal - pathogenicity; Spores, Fungal - physiology; Tryptamines - biosynthesis; Tryptamines - immunology; Tryptamines - pharmacology; Tyramine - biosynthesis; Tyramine - immunology; Tyramine - pharmacology; Poaceae; serotonin; barley; dimer; Bipolaris sorokiniana
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1080/09168451.2017.1290520

The inducible metabolites were analyzed in barley leaves inoculated with Bipolaris sorokiniana, the causal agent of spot blotch of barley. HPLC analysis revealed that B. sorokiniana-infected leaves accumulated 4 hydrophilic compounds. They were purified by ODS column chromatography and preparative HPLC. Spectroscopic analyses revealed that they were tyramine (1), 3-(2-aminoethyl)-3-hydroxyindolin-2-one (2), serotonin (3), and 5,5′-dihydroxy-2,4′-bitryptamine (4). Among these, 2 and 4 have not been reported as natural products. They showed antifungal activity in an assay of inhibition of B. sorokiniana conidia germination, suggesting that they play a role in the chemical defense of barley as phytoalexins. The accumulation of 1-4 was examined also in the leaves of rice and foxtail millet. Rice leaves accumulated 2, 3, and 4, whereas foxtail millet leaves accumulated 3 and 4 in response to pathogen attack, suggesting the generality of accumulation of 3 and 4 in the Poaceae species.