Silencing of the Mitochondrial Ascorbate Synthesizing Enzyme l-Galactono-1,4-Lactone Dehydrogenase Affects Plant and Fruit Development in Tomato
Open Access
- 5 October 2007
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 145 (4), 1408-1422
- https://doi.org/10.1104/pp.107.106500
Abstract
L-Galactono-1,4-lactone dehydrogenase (EC 1.3.2.3) catalyzes the last step in the main pathway of vitamin C (l-ascorbic acid) biosynthesis in higher plants. In this study, we first characterized the spatial and temporal expression of SlGalLDH in several organs of tomato (Solanum lycopersicum) plants in parallel with the ascorbate content. P35S:SlgalldhRNAi silenced transgenic tomato lines were then generated using an RNAi strategy to evaluate the effect of any resulting modification of the ascorbate pool on plant and fruit development. In all P35S:SlgalldhRNAi plants with reduced SlGalLDH transcript and activity, plant growth rate was decreased. Plants displaying the most severe effects (dwarf plants with no fruit) were excluded from further analysis. The most affected lines studied exhibited up to an 80% reduction in SlGalLDH activity and showed a strong reduction in leaf and fruit size, mainly as a consequence of reduced cell expansion. This was accompanied by significant changes in mitochondrial function and altered ascorbate redox state despite the fact that the total ascorbate content remained unchanged. By using a combination of transcriptomic and metabolomic approaches, we further demonstrated that several primary, like the tricarboxylic acid cycle, as well as secondary metabolic pathways related to stress response were modified in leaves and fruit of P35S:SlgalldhRNAi plants. When taken together, this work confirms the complexity of ascorbate regulation and its link with plant metabolism. Moreover, it strongly suggests that, in addition to ascorbate synthesis, GalLDH could play an important role in the regulation of cell growth-related processes in plants.Keywords
This publication has 61 references indexed in Scilit:
- Light regulation of ascorbate biosynthesis is dependent on the photosynthetic electron transport chain but independent of sugars in ArabidopsisJournal of Experimental Botany, 2007
- Arabidopsis VTC2 Encodes a GDP-l-Galactose Phosphorylase, the Last Unknown Enzyme in the Smirnoff-Wheeler Pathway to Ascorbic Acid in PlantsOnline Journal of Public Health Informatics, 2007
- The missing step of the l -galactose pathway of ascorbate biosynthesis in plants, an l -galactose guanyltransferase, increases leaf ascorbate contentProceedings of the National Academy of Sciences of the United States of America, 2007
- Calcium Signaling via Phospholipase C Is Essential for Proline Accumulation upon Ionic But Not Nonionic Hyperosmotic Stresses in ArabidopsisPlant Physiology, 2007
- Ascorbate Oxidase-Dependent Changes in the Redox State of the Apoplast Modulate Gene Transcript Accumulation Leading to Modified Hormone Signaling and Orchestration of Defense Processes in TobaccoPlant Physiology, 2006
- Changes in Transcriptional Profiles Are Associated with Early Fruit Tissue Specialization in TomatoPlant Physiology, 2005
- Ascorbate content of wheat leaves is not determined by maximal l‐galactono‐1,4‐lactone dehydrogenase (GalLDH) activity under drought stressPlant, Cell & Environment, 2005
- Metabolic Profiling Allows Comprehensive Phenotyping of Genetically or Environmentally Modified Plant SystemsPlant Cell, 2001
- Ethylene‐regulated gene expression in tomato fruit: characterization of novel ethylene‐responsive and ripening‐related genes isolated by differential displayThe Plant Journal, 1999
- ASCORBATE AND GLUTATHIONE: Keeping Active Oxygen Under ControlAnnual Review of Plant Physiology and Plant Molecular Biology, 1998