Understanding the biochemical basis of temperature induced lipid pathway adjustments in plants
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One of the cellular responses to temperature fluctuations in plants is the adjustment in the degree of membrane unsaturation. Glycerolipids are major constituents of cellular membranes. In higher plants, glycerolipids are synthesized via two major metabolic pathways compartmentalized in the ER and chloroplast. Adaptive responses in membrane lipids include alterations in fatty acid desaturation, proportional changes in membrane lipids as well as molecular composition of each lipid species. In this study, I systematically explored the significance of glycerolipid pathway balance in temperature induced lipid composition changes in three plant species that have distinctive modes of lipid pathway interactions through a combination of biochemical and molecular approaches including lipidomics and RNA-seq analysis. In Arabidopsis thaliana, a 16:3 plant, low temperature induces an augmented prokaryotic pathway, whereas high temperature enhances the eukaryotic pathway. Atriplex lentiformis reduces its overall lipid desaturation at high temperature and switches lipid phenotype from 16:3 to 18:3 through drastically increasing the contribution of the eukaryotic pathway as well as suppression of the prokaryotic pathway. In sync with the metabolic changes, coordinated expression of glycerolipid pathway genes, as revealed by RNA-seq also occurs. In Triticum aestivum, an 18:3 plant, low temperature leads to a reduced glycerolipid flux from ER to chloroplast. Evidence of differential trafficking of diacylglycerol (DAG) moieties from ER to chloroplast was uncovered in three plant species as another layer of metabolic adaptation under different temperatures. Taken together, this study has established a biochemical basis that highlights the predominance and prevalence of lipid pathway interactions in temperature induced lipid compositional changes.
DegreeDoctor of Philosophy (Ph.D.)
SupervisorZou, Jitao; Wei, Yangdou
CommitteeBonham-Smith, Peta; Gray, Gordon; Wilson, Kenneth
Copyright DateApril 2014
fatty acid metabolism