Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle

Peter J. Eastmond, Veronique Germain, Peter R. Lange, James H. Bryce, Steven M. Smith, Ian A. Graham

    Research output: Contribution to journalArticle

    Abstract

    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.

    Original languageEnglish
    Pages (from-to)5669-5674
    Number of pages6
    JournalProceedings of the National Academy of Sciences
    Volume97
    Issue number10
    Publication statusPublished - 9 May 2000

    Fingerprint

    glyoxylate cycle
    oilseeds
    metabolism
    lipids
    seedlings
    mutants
    photosynthesis
    isocitrate lyase
    oilseed crops
    carbon
    peroxisomes
    light intensity
    mitochondria
    photoperiod
    acetates
    Arabidopsis
    sucrose
    germination
    carbohydrates
    fatty acids

    Cite this

    Eastmond, P. J., Germain, V., Lange, P. R., Bryce, J. H., Smith, S. M., & Graham, I. A. (2000). Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle. Proceedings of the National Academy of Sciences, 97(10), 5669-5674.
    Eastmond, Peter J. ; Germain, Veronique ; Lange, Peter R. ; Bryce, James H. ; Smith, Steven M. ; Graham, Ian A. / Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle. In: Proceedings of the National Academy of Sciences. 2000 ; Vol. 97, No. 10. pp. 5669-5674.
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    abstract = "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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    Eastmond, PJ, Germain, V, Lange, PR, Bryce, JH, Smith, SM & Graham, IA 2000, 'Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle', Proceedings of the National Academy of Sciences, vol. 97, no. 10, pp. 5669-5674.

    Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle. / Eastmond, Peter J.; Germain, Veronique; Lange, Peter R.; Bryce, James H.; Smith, Steven M.; Graham, Ian A.

    In: Proceedings of the National Academy of Sciences, Vol. 97, No. 10, 09.05.2000, p. 5669-5674.

    Research output: Contribution to journalArticle

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    Eastmond PJ, Germain V, Lange PR, Bryce JH, Smith SM, Graham IA. Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle. Proceedings of the National Academy of Sciences. 2000 May 9;97(10):5669-5674.