Antimicrobial activity of UV-induced phenylamides from rice leaves.
Rice produces a wide array of phytoalexins in response to pathogen attacks and UV-irradiation. Except for the flavonoid sakuranetin, most phytoalexins identified in rice are diterpenoid compounds. Analysis of phenolic-enriched fractions from UV-treated rice leaves showed that several phenolic compounds in addition to sakuranetin accumulated remarkably in rice leaves. We isolated two compounds from UV-treated rice leaves using silica gel column chromatography and preparative HPLC. The isolated phenolic compounds were identified as phenylamide compounds: N-trans-cinnamoyltryptamine and N-p-coumaroylserotonin. Expression analysis of biosynthetic genes demonstrated that genes for arylamine biosynthesis were upregulated by UV irradiation. This result suggested that phenylamide biosynthetic pathways are activated in rice leaves by UV treatment. To unravel the role of UV-induced phenylamides as phytoalexins, we examined their antimicrobial activity against rice fungal and bacterial pathogens. N-trans-Cinnamoyltryptamine inhibited the growth of rice brown spot fungus (Bipolaris oryzae). In addition to the known antifungal activity to the blast fungus, sakuranetin had antimicrobial activity toward B. oryzae and Rhizoctonia solani (rice sheath blight fungus). UV-induced phenylamides and sakuranetin also had antimicrobial activity against rice bacterial pathogens for grain rot (Burkholderia glumae), blight (Xanthomonas oryzae pv. oryzae) and leaf streak (X. oryzae pv. oryzicola) diseases. These findings suggested that the UV-induced phenylamides in rice are phytoalexins against a diverse array of pathogens.
Graduate School of Biotechnology, Kyung Hee University, Yongin 446-70, Korea. hlpark@khu.ac.kr.
Hye Lin
HL
Park
Department of Plant Molecular Systems Biotechnology & Crop Biotech Institute, Kyung Hee University, Yongin 446-70, Korea. yooyc@khu.ac.kr.
Youngchul
Y
Yoo
Graduate School of Biotechnology, Kyung Hee University, Yongin 446-70, Korea. trhahn@khu.ac.kr.
Tae-Ryong
TR
Hahn
Graduate School of Biotechnology, Kyung Hee University, Yongin 446-70, Korea. shbhoo@khu.ac.kr.
Seong Hee
SH
Bhoo
Department of Plant Molecular Systems Biotechnology & Crop Biotech Institute, Kyung Hee University, Yongin 446-70, Korea. swlee6803@khu.ac.kr.
Sang-Won
SW
Lee
Graduate School of Biotechnology, Kyung Hee University, Yongin 446-70, Korea. manhocho@khu.ac.kr.
Man-Ho
MH
Cho
D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D001203:Ascomycota / Q000254:growth & development*; D001679:Biogenic Amines / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D019117:Burkholderia / Q000254:growth & development*; D005786:Gene Expression Regulation; D012275:Oryza / Q000737:chemistry / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D012232:Rhizoctonia / Q000254:growth & development*; D014466:Ultraviolet Rays; D014974:Xanthomonas / Q000254:growth & development*
D000890:Anti-Infective Agents; D001679:Biogenic Amines