|
|
||||||||
|
First published online July 9, 2004; 10.1104/pp.104.039511 Plant Physiology 135:1574-1582 (2004) © 2004 American Society of Plant Biologists A Novel Inhibitor of 9-cis-Epoxycarotenoid Dioxygenase in Abscisic Acid Biosynthesis in Higher Plants1RIKEN, Wako, Saitama 3510198, Japan (S.-Y.H., N.K., K.S., S.Y., T.A.); Department of Biological and Environmental Sciences, Graduate School of Science and Engineering, Saitama University, Saitama 3388570, Japan (S.-Y.H., N.K., K.S., S.Y.); RIKEN Tsukuba Institute, Tsukuba, Ibaraki 3050074, Japan (T.S., K.S.); RIKEN Tsukuba Institute, BioResource Center, Tsukuba, Ibaraki 3050074, Japan (M.K.); and Biological Resources Division, Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki 3058686, Japan (K.N., K.Y.-S.)
Abscisic acid (ABA) is a major regulator in the adaptation of plants to environmental stresses, plant growth, and development. In higher plants, the ABA biosynthesis pathway involves the oxidative cleavage of 9-cis-epoxycarotenoids, which may be the key regulatory step in the pathway catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED). We developed a new inhibitor of ABA biosynthesis targeting NCED and named it abamine (ABA biosynthesis inhibitor with an amine moiety). Abamine is a competitive inhibitor of NCED, with a Ki of 38.8 µM. In 0.4 M mannitol solution, which mimics the effects of osmotic stress, abamine both inhibited stomatal closure in spinach (Spinacia oleracea) leaves, which was restored by coapplication of ABA, and increased luminescence intensity in transgenic Arabidopsis containing the RD29B promoter-luciferase fusion. The ABA content of plants in 0.4 M mannitol was increased approximately 16-fold as compared with that of controls, whereas 50 to 100 µM abamine inhibited about 50% of this ABA accumulation in both spinach leaves and Arabidopsis. Abamine-treated Arabidopsis was more sensitive to drought stress and showed a significant decrease in drought tolerance than untreated Arabidopsis. These results suggest that abamine is a novel ABA biosynthesis inhibitor that targets the enzyme catalyzing oxidative cleavage of 9-cis-epoxycarotenoids. To test the effect of abamine on plants other than Arabidopsis, it was applied to cress (Lepidium sativum) plants. Abamine enhanced radicle elongation in cress seeds, which could be due to a decrease in the ABA content of abamine-treated plants. Thus, it is possible to think that abamine should enable us to elucidate the functions of ABA in cells or plants and to find new mutants involved in ABA signaling.
1 This work was supported in part by the Bioarchitect Research Program at RIKEN, funded by the Science and Technology Agency of Japan. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.039511. * Corresponding author; e-mail tasami{at}postman.riken.go.jp; fax 81484624674. Received January 20, 2004; returned for revision April 15, 2004; accepted May 5, 2004. Related articles in Plant Physiol.:
This article has been cited by other articles:
|
|||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY® | THE PLANT CELL | |
|---|---|---|---|