Characterization of an Arabidopsis mutant deficient in γ-tocopherol methyltransferase

Characterization of an Arabidopsis mutant deficient in γ-tocopherol methyltransferase Alpha-tocopherol (vitamin E) is synthesized from γ-tocopherol in chloroplasts by γ-tocopherol methyltransferase (γ-TMT; VTE4). Leaves of many plant species including Arabidopsis contain high levels of α-tocopherol, but are low in γ-tocopherol. To unravel the function of different forms of tocopherol in plants, an Arabidopsis plant (vte4-1) carrying a functional null mutation in the gene γ-TMT was isolated by screening a mutant population via thin-layer chromatography. A second mutant allel (vte4-2) carrying a T-DNA insertion in the coding sequence of γ-TMT was identified in a T-DNA tagged mutant population. In vte4-1 and vte4-2 leaves, high levels of γ-tocopherol accumulated, whereas α-tocopherol was absent indicating that, presumably, these two mutants represents null alleles. Over-expression of the γ-TMT cDNA in vte4-1 restored wild-type tocopherol composition. Mutant plants were very similar to wild type. During oxidative stress (high light, high temperature, cold treatment) the amounts of α-tocopherol and γ-tocopherol increased in wild type, and γ-tocopherol in vte4-1. However, chlorophyll content and photosynthetic quantum yield were very similar in wild type and vte4-1, suggesting that α-tocopherol can be replaced by γ-tocopherol in vte4-1 to protect the photosynthetic apparatus against oxidative stress. Fatty acid and lipid composition were very similar in WT, vte4-1 and vte1, an Arabidopsis mutant previously isolated which is completely devoid of tocopherol. Therefore, a shift in tocopherol composition or the absence of tocopherol has no major impact on the amounts of specific fatty acids or on lipid hydrolysis. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

Characterization of an Arabidopsis mutant deficient in γ-tocopherol methyltransferase

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Publisher
Springer Journals
Copyright
Copyright © 2003 by Kluwer Academic Publishers
Subject
Life Sciences; Biochemistry, general; Plant Sciences; Plant Pathology
ISSN
0167-4412
eISSN
1573-5028
D.O.I.
10.1023/B:PLAN.0000004307.62398.91
Publisher site
See Article on Publisher Site

Abstract

Alpha-tocopherol (vitamin E) is synthesized from γ-tocopherol in chloroplasts by γ-tocopherol methyltransferase (γ-TMT; VTE4). Leaves of many plant species including Arabidopsis contain high levels of α-tocopherol, but are low in γ-tocopherol. To unravel the function of different forms of tocopherol in plants, an Arabidopsis plant (vte4-1) carrying a functional null mutation in the gene γ-TMT was isolated by screening a mutant population via thin-layer chromatography. A second mutant allel (vte4-2) carrying a T-DNA insertion in the coding sequence of γ-TMT was identified in a T-DNA tagged mutant population. In vte4-1 and vte4-2 leaves, high levels of γ-tocopherol accumulated, whereas α-tocopherol was absent indicating that, presumably, these two mutants represents null alleles. Over-expression of the γ-TMT cDNA in vte4-1 restored wild-type tocopherol composition. Mutant plants were very similar to wild type. During oxidative stress (high light, high temperature, cold treatment) the amounts of α-tocopherol and γ-tocopherol increased in wild type, and γ-tocopherol in vte4-1. However, chlorophyll content and photosynthetic quantum yield were very similar in wild type and vte4-1, suggesting that α-tocopherol can be replaced by γ-tocopherol in vte4-1 to protect the photosynthetic apparatus against oxidative stress. Fatty acid and lipid composition were very similar in WT, vte4-1 and vte1, an Arabidopsis mutant previously isolated which is completely devoid of tocopherol. Therefore, a shift in tocopherol composition or the absence of tocopherol has no major impact on the amounts of specific fatty acids or on lipid hydrolysis.

Journal

Plant Molecular BiologySpringer Journals

Published: Oct 7, 2004

References

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