Genetic engineering of potato (Solanum tuberosum L.) for enhanced α-tocopherols and abiotic stress tolerance

Vitamin E (α-tocopherol) is a lipid-soluble essential vitamin recognized for improvement in degenerative health conditions, abating cancer risk, and coronary heart diseases in humans. While in plants, it acts as a free radical scavenger that protects cells against oxidative and photooxidative damages. The daily consumption of potato makes it a key target for biofortification with vitamins for eliminating vitamin deficiency in large populations. Vitamin E biosynthetic pathway genes have been overexpressed in plants via genetic engineering to enhance the α-tocopherol content. Major genes involved in the vitamin E biosynthesis in plants viz. the homogentisate-phytyltransferase (At-HPT) and γ-tocopherol-methyltransferase (At-γ-TMT), isolated from Arabidopsis were constitutively overexpressed in potato (Solanum tuberosum L.). The molecular analyses of independent transgenic lines revealed a stable integration of both the genes in the plant genome. The transgenic potato exhibited significantly improved vitamin E contents up to 173-258% in comparison to the untransformed control plants. Transgenic tissues also exhibited increased cellular antioxidant enzymes, proline, osmolyte, and glutathione content that are directly correlated with the ability of the plant to withstand abiotic stresses imposed by salt (NaCl) and heavy metal (CdCl₂ ). Therefore, the current strategy of increasing the vitamin E content in potato with enhanced tolerance to abiotic stresses might greatly aid efforts to engineer crops for human health benefits and greater yield under adverse environmental conditions.