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First published online December 16, 2005; 10.1104/pp.105.071167 Plant Physiology 140:263-278 (2006) © 2006 American Society of Plant Biologists Repressing the Expression of the SUCROSE NONFERMENTING-1-RELATED PROTEIN KINASE Gene in Pea Embryo Causes Pleiotropic Defects of Maturation Similar to an Abscisic Acid-Insensitive Phenotype1,[W]Institut für Pflanzengenetik und Kulturpflanzenforschung, D–06466 Gatersleben, Germany
The classic role of SUCROSE NONFERMENTING-1 (Snf1)-like kinases in eukaryotes is to adapt metabolism to environmental conditions such as nutrition, energy, and stress. During pea (Pisum sativum) seed maturation, developmental programs of growing embryos are adjusted to changing physiological and metabolic conditions. To understand regulation of the switch from cell proliferation to differentiation, SUCROSE NONFERMENTING-1-RELATED PROTEIN KINASE (SnRK1) was antisense repressed in pea seeds. Transgenic seeds show maturation defects, reduced conversion of sucrose into storage products, lower globulin content, frequently altered cotyledon surface, shape, and symmetry, as well as occasional precocious germination. Gene expression analysis of embryos using macroarrays of 5,548 seed-specific genes revealed 183 differentially expressed genes in two clusters, either delayed down-regulated or delayed up-regulated during transition. Delayed down-regulated genes are related to mitotic activity, gibberellic acid/brassinosteroid synthesis, stress response, and Ca2+ signal transduction. This specifies a developmentally younger status and conditional stress. Higher gene expression related to respiration/gluconeogenesis/fermentation is consistent with a role of SnRK1 in repressing energy-consuming processes in maturing cotyledons under low oxygen/energy availability. Delayed up-regulated genes are mainly related to storage protein synthesis and stress tolerance. Most of the phenotype resembles abscisic acid (ABA) insensitivity and may be explained by reduced Abi-3 expression. This may cause a reduction in ABA functions and/or a disconnection between metabolic and ABA signals, suggesting that SnRK1 is a mediator of ABA functions during pea seed maturation. SnRK1 repression also impairs gene expression associated with differentiation, independent from ABA functions, like regulation and signaling of developmental events, chromatin reorganization, cell wall synthesis, biosynthetic activity of plastids, and regulated proteolysis.
1 This work was supported by the Deutsche Forschungsgemeinschaft and by Institut für Pflanzengenetik und Kulturpflanzenforschung (cDNA sequencing). The author responsible for distribution of materials integral to the findings presented in this article in accordance with journal policy described in the Instructions for Authors (http://www.plantphysiol.org) is: Hans Weber (weber{at}ipk-gatersleben.de). [W] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.071167. * Corresponding author; e-mail weber{at}ipk-gatersleben.de; fax 49–39482–5500. Received September 8, 2005; returned for revision November 1, 2005; accepted November 1, 2005. This article has been cited by other articles:
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