MPI für molekulare Pflanzenphysiologie / Publikationen Pflanzenphysiologie |
|Characterization of an Arabidopsis mutant deficient in gamma-tocopherol methyltransferase|
|Authors:||Bergmuller, E.; Porfirova, S.; Doermann, P.|
|Date of Publication (YYYY-MM-DD):||2003|
|Title of Journal:||Plant Molecular Biology|
|Issue / Number:||6|
|Review Status:||not specified|
|Abstract / Description:||Alpha-tocopherol (vitamin E) is synthesized from gamma-tocopherol in chloroplasts by gamma-tocopherol methyltransferase (gamma-TMT; VTE4). Leaves of many plant species including Arabidopsis contain high levels of alpha-tocopherol, but are low in gamma-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 gamma-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 gamma-TMT was identified in a T-DNA tagged mutant population. In vte4-1 and vte4-2 leaves, high levels of gamma-tocopherol accumulated, whereas alpha-tocopherol was absent indicating that, presumably, these two mutants represents null alleles. Over-expression of the gamma-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 alpha-tocopherol and gamma-tocopherol increased in wild type, and gamma-tocopherol in vte4-1. However, chlorophyll content and photosynthetic quantum yield were very similar in wild type and vte4-1, suggesting that alpha-tocopherol can be replaced by gamma-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. [References: 43] 43|
|Free Keywords:||P-hydroxyphenylpyruvate dioxygenase. Homogentisate phytyltransferase.
; Spinach-chloroplasts. Lipid-peroxidation. Higher-plants. Vitamin-e.
; Biosynthesis. Localization. Thaliana. Prenylquinones.
; Plant Sciences in Current Contents(R)/Agricultural, Biology &
; Environmental Sciences
; Animal & Plant Sciences in Current Contents(R)/Life Sciences.
; 2003 week 50
|External Publication Status:||published|
|Communicated by:||N. N.|
|Affiliations:||MPI für molekulare Pflanzenphysiologie/Molekulare Physiologie/AG Doermann|
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