Arabidopsis Aleurone Layer Responds to Nitric Oxide, Gibberellin, and Abscisic Acid and Is Sufficient and Necessary for Seed Dormancy

• Published in: Plant physiology (Bethesda) Vol. 143; no. 3; pp. 1173 - 1188
• Main Authors: Bethke, Paul C, Libourel, Igor G.L, Aoyama, Natsuyo, Chung, Yong-Yoon, Still, David W, Jones, Russell L
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-03-2007; American Society of Plant Physiologists
• Subjects: Abscisic Acid - pharmacology; Aleurone cells; Aleurone layer; Arabidopsis - drug effects; Arabidopsis - embryology; Arabidopsis - growth & development; Biological and medical sciences; Cell walls; Cyclic N-Oxides - pharmacology; Development and Hormone Action; Dormancy; Embryos; Fundamental and applied biological sciences. Psychology; Germination; Germination - drug effects; Germination and dormancy; Gibberellins - pharmacology; Imidazoles - pharmacology; Nitric Oxide - pharmacology; Plant Growth Regulators - pharmacology; Plant physiology and development; Plants; Seed dormancy; Seeds - anatomy & histology; Seeds - drug effects; Seeds - growth & development; Signal Transduction; Testa; Vacuoles; Vacuoles - drug effects; Vacuoles - metabolism; Dormancy; Aleurone; Seeds; Cruciferae; Arabidopsis; Dicotyledones; Nitric oxide; Angiospermae; Abscisic acid; Gibberellin; Spermatophyta
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.106.093435

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.