Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 46 3 2015 09 23 Investigation of Tocopherol cyclase gene overexpression effects on the drought stress tolerance by using of tabacco (Nicotiana tabacum) transgenic plants Investigation of Tocopherol cyclase gene overexpression effects on the drought stress tolerance by using of tabacco (Nicotiana tabacum) transgenic plants 413 422 55845 10.22059/ijfcs.2015.55845 FA Nahid Ranaeian M. Sc. Student, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Alireza Abbasi Assistant Professor, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Hassan Zeinali Khanghah Associate Professor, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Journal Article 2014 06 22 Environmental stresses trigger a wide variety of plant responses, such as altered gene expression to changes in cellular metabolism and growth. The several plant reactions exist to circumvent the potentially harmful effects caused by light, drought, salinity, pathogen infections and other stresses. a-Tocopherol is the major vitamin E compound found in leaf chloroplasts. This antioxidant deactivates photosynthesis-derived reactive oxygen species and prevents the propagation of lipid peroxidation by scavenging lipid peroxyl radicals in thylakoid membranes. In this study, we used the  tabacco plants containing of pBin:At.TC  construct that overexpressed the tocopherol cyclase gene. For analysis effect of  overexpressed this gene, the transgenic plants were subjected to drought stress and were studied number of physiologic parameters such as, chlorophyls and carotenoid, proline amino acid content, relative water content,  membrane permeability, in transgenic and wild type plants in  normal and drought stress condition. The results indicated that transgenic plants have increased chlorophyl, proline and relative water content and decreased membrane Permeability in 40 and 60 stress levels, in comparison to wild type plants. Therefore the overexpression of tocopherol cyclase gene in tabacco plants maybe cause increased plant tolerance under drought stress conditions. Environmental stresses trigger a wide variety of plant responses, such as altered gene expression to changes in cellular metabolism and growth. The several plant reactions exist to circumvent the potentially harmful effects caused by light, drought, salinity, pathogen infections and other stresses. a-Tocopherol is the major vitamin E compound found in leaf chloroplasts. This antioxidant deactivates photosynthesis-derived reactive oxygen species and prevents the propagation of lipid peroxidation by scavenging lipid peroxyl radicals in thylakoid membranes. In this study, we used the  tabacco plants containing of pBin:At.TC  construct that overexpressed the tocopherol cyclase gene. For analysis effect of  overexpressed this gene, the transgenic plants were subjected to drought stress and were studied number of physiologic parameters such as, chlorophyls and carotenoid, proline amino acid content, relative water content,  membrane permeability, in transgenic and wild type plants in  normal and drought stress condition. The results indicated that transgenic plants have increased chlorophyl, proline and relative water content and decreased membrane Permeability in 40 and 60 stress levels, in comparison to wild type plants. Therefore the overexpression of tocopherol cyclase gene in tabacco plants maybe cause increased plant tolerance under drought stress conditions. https://ijfcs.ut.ac.ir/article_55845_4a16ec86b6e0130ca2afe2c6a9fe2de6.pdf