The Relationship Between Tocopherol Cyclase Gene(VTE1) From Arabidopsis And Content Of Vitamin E And Tolerance In Tobacco W38

Tocopherol is also called vitamin E (VE), it is one kind of the important lipophilic antioxidant on cell membrane for plants under the stressful environments. Tocopherol cyclase (TC) catalyzes the conversion of various phytyl quinol pathway intermediates to their corresponding tocopherols through the formation of the chromanol ring. In this study, tobacco W38 was transformed with a construct containing a cDNA insert encoding tocopherol cyclase (VTE1) from Arabidopsis under the control of the cauliflower mosaic virus (CaMV) 35S promoter and we examine if the content of VE in transgenic tobacco plants increase with the over-expression of VTE1, and then study the improve effect of VTE1 from Arabidopsis on the content of VE in tobacco. Based on the fact that the level of tocopherols vary with the stress level outside, we studied the endurance of transgenic tobacco plants to high light and salinity, in order to provide the exact evidence for the relationship between the tocopherols of high content and the stress condition, form a solid foundation for the study of the mechanism and utility of endurance in plants, The main results were as follows:The ten transgenic tobacco plants were confirmed by Southern blot and RT-PCR analyses, which lead the same PCR product of 495 bp as the positive control. Compared to the wild type controls, the content of vitamin E in transgenic lines was two times higher than that in the wild type, the most was 11.32 times, which showed that TC is the important limiting enzyme in the biosynthesis of tocopherols. The over-expression of VTE1 could increase the content of tocopherols effectively.The endurance of transgenic plants was higher than that of the wild type to salinity stress on their phenotype, which showed on the withered areas of leaves. In different salinities(150,250 mmol/L), the content of tocopherols in transgenic lines was 1.3-1.8 higher than that in wild type, which indicated that the over-expression of VTE1 had increased the salt stress tolerance in tobacco plants.Meanwhile, the content of proline in wild type increased with the increase of salinity, but it increased first and then decreased in transgenic tobacco. The content of...