| Abstract Detail
Oxidative Stress Maeda, Hiroshi [1], Sage, Tammy [2], DellaPenna, Dean [3]. Role of tocopherols in lipid metabolism and phloem loading during chilling adaptation in Arabidopsis. Tocopherols (vitamin E) are the major class of lipid-soluble antioxidants in biological membranes and are produced by all plants and algae, and many cyanobacteria. We have previously reported that tocopherols have a surprisingly limited role in photoprotection but play a crucial role in phloem loading during chilling adaptation in plants (Maeda et al., 2006). The vitamin E deficient 2 (vte2) mutant of Arabidopsis thaliana was chilling sensitive due to impaired photoassimilate export, which temporally correlated with alterations to phloem transfer cell wall structure. In this study, vte2 exhibited a distinct composition of polyunsaturated fatty acids [PUFAs; i.e. decreased linolenic acid (18:3) and increased linoleic acid (18:2)] in response to low temperature in comparison to wild type. The alterations to PUFAs in vte2 occurred primarily in the fatty acids esterified to lipids derived from the endoplasmic-reticulum (ER) pathway. 14C-radiolabel tracer studies are consistent with impact in the conversion of dienoic to trienoic fatty acids (e.g. 18:2 to 18:3) at the ER membrane in vte2. Finally, introduction of fatty acid desaturase 2 (fad2), an ER omega6 fatty acid desaturase mutation, into the vte2 background resulted in near complete suppression of the vte2-chilling phenotypes including both impaired photoassimilate export and altered phloem transfer cell wall structure. Together these results suggest that tocopherols modulate extra-plastidic pathway-derived PUFAs and thereby play a crucial role in phloem loading and chilling adaptation in Arabidopsis.
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Maeda H, Song W, Sage TL and DellaPenna D (2006) Plant Cell 18, 2710-2732
1 - Michigan State University, Department of Biochemistry and Molecular Biology, 201 Biochemistry, East Lansing, MI, 48824, USA
2 - University of Toronto, Department of Botany
3 - Michigan State University, Department of Biochemistry and Molecular Biology
Keywords:
tocopherol
antioxidant
vitamin E
low temperature
membrane
phloem loading.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P06008
Abstract ID:326 |
