Poster: Lipids & related molecules
Abs #
310: Fatty acid accumulation profile of tobacco chloroplasts expressing a 3-hydroxysteroid oxidase gene.
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Presenter: |
Bedard, Mark , BedardM@canisius.edu |
Authors | Bedard, Mark (A) Ruffino, John (A) Fordyce, Amber (A) DeWitt, Matt (A) Heyer, Jannelle (A) Parker, Brandon (A) Becker, David (B) Grebenok, Robert (A) | | Affiliations: |
(A): Canisius College, Department of Biology
(B): Pomona College, Department of Biology
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The requirement of a particular mixture of sterol and fatty acid to modulate the fluidity of biological membranes within higher plants is obvious, however little information exists regarding the influence of increased steroid levels on fatty acid accumulation throughout the plant. Transgenic plants expressing a 3-hydroxysteroid oxidase within the chloroplast demonstrate a 6-fold increase in steroid accumulation. The 3-hydroxysteroid oxidase enzyme is responsible for facilitating the conversion of sterol to stanol culminating in the accumulation of elevated levels of sterols including stigmasterol and cholesterol, the 3-ketosteroids cholestan-3-one, campestan-3-one and sitostan-3-one and the stanols cholestanol, campestanol and sitostanol within the transgenic plants. Chloroplasts, the site of 3-hydroxysteroid oxidase expression, are typically considered steroid poor organelles however past and current results demonstrate a large mass of sterol is moving through the organelle. The modified sterol budget of the transgenic plants correlates with a two fold increase in photosynthetic efficiency measured in isolated chloroplasts obtained from plants grown at 22oC demonstrating a modified membrane environment. No morphological abnormalities of consequence are noted in plants maintaining 3-hydroxysteroid oxidase expression implying that fatty acid content of the chloroplasts are changing relative to the accumulation of altered steroids. The relationship between the steroid accumulation pattern, fatty acid accumulation pattern and chloroplast physiology is discussed.
