Vitamin E may be gaining attention as a cancer-fighting antioxidant in humans, but a recent study has shown that vitamin E also plays a crucial role in helping plants reproduce in cold temperatures by assisting in seed production.“When plants are in the cold…vitamin E is very important for adaptation of those plants to continue, to make seeds in that cold environment,” explained Tammy Sage from U of T’s department of ecology and evolutionary biology, who reported her findings in a recent issue of The Plant Cell in collaboration with scientists from the University of Michigan. In animal systems, vitamin E acts as an antioxidant and protects animal cells from the destructive effects of free radicals. A long-held hypothesis stated that vitamin E prevents similar damage to the choloroplasts of plant cells and could be important for maintaining a plant’s photosynthetic machinery. To test this theory, Sage and her collaborators created mutant Arabidopsis thaliana plants whose levels of vitamin E and its intermediates were below normal, and analyzed the plants’ responses to different kinds of stress, such as salinity, high light, cold temperature and drought. “Under stress conditions, it is very clear that within a leaf, vitamin E does not assist as an antioxidant with respect to photosynthetic processes,” concluded Sage. Instead of observing defects in photosynthesis as would be expected in a plant that lacks the antioxidant power of vitamin E, Sage and her collaborators observed a build-up of sugar in the leaves of mutant plants under cold conditions, as well as a reduction in the number of seeds in such mutants. Photosynthesis was not affected by a lack of vitamin E. “In normal plants, vitamin E functions to transport sugars in the leaves, where sugar is made, to other parts of the plant where sugars are consumed.” In Sage’s mutants, transfer cells, responsible for distributing nutrients, accumulate a carbohydrate called callose in their cell walls, preventing the movement of nutrients to other parts of the plants, such as the seeds. As a result, the mutant plants suffered a reduction in the number and the quality of seeds. These findings could be great news for the farmers in Canada who are seeking ways to grow plants, such as flax, better in the great Canadian cold. “In Canada, where we have a shorter growing season, modifying [plants] for enhanced cold tolerance may mean giving them a little more vitamin E,” noted Sage. In addition, the large amount of sugar in the leaves of the vitamin E-deficient mutants makes the leaves good raw materials for biofuel production, eliminating most of the need to break down cellulose into sugar, which requires a lot of energy.
Published: 9:00 am, 28 November 2006
Modified: 5:57 pm, 11 January 2012