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First published online January 12, 2007; 10.1104/pp.106.093435 Plant Physiology 143:1173-1188 (2007) © 2007 American Society of Plant Biologists OPEN ACCESS ARTICLE
The Arabidopsis Aleurone Layer Responds to Nitric Oxide, Gibberellin, and Abscisic Acid and Is Sufficient and Necessary for Seed Dormancy1,[C],[W],[OA]United States Department of Agriculture, Agricultural Research Service, Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706 (P.C.B.); Department of Plant and Microbial Biology, University of California, Berkeley, California 94720 (P.C.B., I.G.L.L., R.L.J.); Michigan State University, East Lansing, Michigan 48824 (I.G.L.L.); Department of Plant Sciences, California State Polytechnic University, Pomona, California 91768 (N.A., D.W.S.); and College of Life Sciences, Korea University, Seoul, Korea 136–152 (Y.-Y.C.)
Seed dormancy is a common phase of the plant life cycle, and several parts of the seed can contribute to dormancy. Whole seeds, seeds lacking the testa, embryos, and isolated aleurone layers of Arabidopsis (Arabidopsis thaliana) were used in experiments designed to identify components of the Arabidopsis seed that contribute to seed dormancy and to learn more about how dormancy and germination are regulated in this species. The aleurone layer was found to be the primary determinant of seed dormancy. Embryos from dormant seeds, however, had a lesser growth potential than those from nondormant seeds. Arabidopsis aleurone cells were examined by light and electron microscopy, and cell ultrastructure was similar to that of cereal aleurone cells. Arabidopsis aleurone cells responded to nitric oxide (NO), gibberellin (GA), and abscisic acid, with NO being upstream of GA in a signaling pathway that leads to vacuolation of protein storage vacuoles and abscisic acid inhibiting vacuolation. Molecular changes that occurred in embryos and aleurone layers prior to germination were measured, and these data show that both the aleurone layer and the embryo expressed the NO-associated gene AtNOS1, but only the embryo expressed genes for the GA biosynthetic enzyme GA3 oxidase.
1 This work was supported by the National Science Foundation (to R.L.J.), by the California Agricultural Research Initiative (to D.W.S.), by the Plant Signal Network Research Center of the Ministry of Science and Technology, and by the Biogreen 21 program of Rural Development Administration Republic of Korea. 2 These authors contributed equally to the paper. 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: Russell L. Jones (rjones{at}nature.berkeley.edu). [C] Some figures in this article are displayed in color online but in black and white in the print edition. [W] The online version of this article contains Web-only data. [OA] Open Access articles can be viewed online without a subscription. www.plantphysiol.org/cgi/doi/10.1104/pp.106.093435 * Corresponding author; e-mail pbethke{at}wisc.edu; fax 608–262–4743. Received November 21, 2006; accepted December 29, 2006; published January 12, 2007. This article has been cited by other articles:
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