Submitted to: International Symposium on Plant Lipids
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2007
Publication Date: 4/1/2007
Citation: Siocombe, S., Cornah, J., Pinfield-Wells, H., Dyer, J.M., Graham, I.A. Role of the fatty acid breakdown pathway in the leaf (abstract). International Symposium on Plant Lipids.
Technical Abstract: Components of the lipid breakdown pathway including beta-oxidation enzymes and fatty acid transport mechanisms are essential for mobilizing storage lipid in germinating seeds of many plants. Comparatively little is known about their role during the rest of the plant’s life-time, however. We are currently examining three key processes where lipid breakdown/turnover is likely to be especially important: a) response to extended dark, b) leaf senescence and c) diurnal cycle. Plants can survive for relatively long periods in extended dark but this is likely to be dependent on re-mobilization of resources including lipids to maintain younger leaves. Senescence of older leaves involves re-mobilization of membrane lipids, especially galactolipids of the plastid membranes, in a controlled process that delays disruption of organelles. Interestingly, lipid turnover during the diurnal cycle is poorly understood either in relation to shifts in lipid composition or in its contribution to metabolism during the dark period. Our chosen approach is to study responses of different lipid breakdown mutants under the three conditions, applying metabolomic, transcriptomic and ultrastructural methodologies. We show here that mutants of beta-oxidation have reduced capacity to survive extended dark. Microarray analysis of the fatty acid transporter mutant (pxa1) after 12h extended dark demonstrates radical changes in the transcriptome reminiscent of stresses such as ozone treatment, salt stress and pathogen attack. Preliminary metabolic analysis suggests that carbohydrate metabolism is accelerated in these conditions in an attempt to compensate for a reduction in lipid breakdown.