|
|
||||||||
|
First published online February 3, 2006; 10.1104/pp.105.070334 Plant Physiology 140:1475-1483 (2006) © 2006 American Society of Plant Biologists Cholic Acid, a Bile Acid Elicitor of Hypersensitive Cell Death, Pathogenesis-Related Protein Synthesis, and Phytoalexin Accumulation in RiceFood and Health R&D Laboratories, Meiji Seika Kaisha, Ltd., Sakado, Saitama 3500289, Japan (J.K., H.K., T.K.); Microbiological Resources and Technology Laboratories, Meiji Seika Kaisha, Ltd., Odawara, Kanagawa 2500852, Japan (S.G.); Agricultural and Veterinary Research Laboratories, Meiji Seika Kaisha, Ltd., Kohoku-ku, Yokohama 2228567, Japan (K.U.); and Department of Bioresource Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 0808555, Japan (M.O.)
When plants interact with certain pathogens, they protect themselves by generating various defense responses. These defense responses are induced by molecules called elicitors. Since long ago, composts fermented by animal feces have been used as a fertilizer in plant cultivation, and recently, have been known to provide suppression of plant disease. Therefore, we hypothesized that the compounds from animal feces may function as elicitors of plant defense responses. As a result of examination of our hypothesis, an elicitor of rice defense responses was isolated from human feces, and its structure was identified as cholic acid (CA), a primary bile acid in animals. Treatment of rice (Oryza sativa) leaves with CA induced the accumulation of antimicrobial compounds (phytoalexins), hypersensitive cell death, pathogenesis-related (PR) protein synthesis, and increased resistance to subsequent infection by virulent pathogens. CA induced these defense responses more rapidly than did fungal cerebroside, a sphingolipid elicitor isolated from the rice pathogenic fungus Magnaporthe grisea. Furthermore, fungal cerebroside induced both types of rice phytoalexins, phytocassanes and momilactones, whereas CA mainly induced phytocassanes, but not momilactones. In the structure-activity relationship analysis, the hydroxyl groups at C-7 and C-12, and the carboxyl group at C-24 of CA contributed to the elicitor activity. These results indicate that CA is specifically recognized by rice and is a different type of elicitor from fungal cerebroside. This report demonstrated that bile acid induced defense responses in plants.
The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jinichiro Koga (jinichiro_koga{at}meiji.co.jp). Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.070334. * Corresponding author; e-mail jinichiro_koga{at}meiji.co.jp; fax 81492847598. Received August 25, 2005; returned for revision November 22, 2005; accepted January 5, 2006. Related articles in Plant Physiol.:
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY® | THE PLANT CELL | |
|---|---|---|---|