Postgerminative Growth and Lipid Catabolism in Oilseeds Lacking the Glyoxylate Cycle
The glyoxylate cycle is regarded as essential for postgerminative growth and seedling establishment in oilseed plants. We have identified two allelic Arabidopsis mutants, icl-1 and icl-2, which lack the glyoxylate cycle because of the absence of the key enzyme isocitrate lyase. These mutants demonst...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 97; no. 10; pp. 5669 - 5674 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences of the United States of America
09.05.2000
National Acad Sciences National Academy of Sciences The National Academy of Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | The glyoxylate cycle is regarded as essential for postgerminative growth and seedling establishment in oilseed plants. We have identified two allelic Arabidopsis mutants, icl-1 and icl-2, which lack the glyoxylate cycle because of the absence of the key enzyme isocitrate lyase. These mutants demonstrate that the glyoxylate cycle is not essential for germination. Furthermore, photosynthesis can compensate for the absence of the glyoxylate cycle during postgerminative growth, and only when light intensity or day length is decreased does seedling establishment become compromised. The provision of exogenous sugars can overcome this growth deficiency. The icl mutants also demonstrate that the glyoxylate cycle is important for seedling survival and recovery after prolonged dark conditions that approximate growth in nature. Surprisingly, despite their inability to catalyze the net conversion of acetate to carbohydrate, mutant seedlings are able to break down storage lipids. Results suggest that lipids can be used as a source of carbon for respiration in germinating oilseeds and that products of fatty acid catabolism can pass from the peroxisome to the mitochondrion independently of the glyoxylate cycle. However, an additional anaplerotic source of carbon is required for lipid breakdown and seedling establishment. This source can be provided by the glyoxylate cycle or, in its absence, by exogenous sucrose or photosynthesis. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 Edited by Christopher R. Somerville, Carnegie Institution of Washington, Stanford, CA, and approved March 1, 2000 To whom reprint requests should be addressed. E-mail: iag@cnap.york.ac.uk. Present address: University of York, Centre for Novel Agricultural Products, Central Science Laboratory, Sand Hutton, York, YO41 1LZ, United Kingdom. Present address: Laboratoire de Biologie Cellulaire et Moleculaire du Developpement des Plantes, Universite de Bordeaux, Avenue des Facultes, 33405 Talence Cedex, France. |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.97.10.5669 |