Improvement of vitamin E quality and quantity in tobacco and lettuce by chloroplast genetic engineering

• DOI: 10.1007/s11248-012-9656-5
• Publication Date: 2012-09-18T17:52:52Z
• Authors: Yukinori Yabuta; Hiroyuki Tanaka; Sahoko Yoshimura; Akiko Suzuki; Masahiro Tamoi; Takanori Maruta; Shigeru Shigeoka
• Keywords: Nicotiana; 0301 basic medicine; 2. Zero hunger; 03 medical and health sciences; Chloroplasts; Humans; Vitamin E; Genetic Engineering; Plants, Genetically Modified; Lactuca

Vitamin E (tocopherol: Toc) is an important lipid-soluble antioxidant synthesized in chloroplasts. Among the 8 isoforms of vitamin E, α-Toc has the highest activity in humans. To generate transgenic plants with enhanced vitamin E activity, we applied a chloroplast transformation technique. Three types of the transplastomic tobacco plants (pTTC, pTTMT and pTTC-TMT) carrying the Toc cyclase (TC) or γ-Toc methyltransferase (γ-TMT) gene and the TC plus γ-TMT genes as an operon in the plastid genome, respectively, were generated. There was a significant increase in total levels of Toc due to an increase in γ-Toc in the pTTC plants. Compared to the wild-type plants, Toc composition was altered in the pTTMT plants. In the pTTC-TMT plants, total Toc levels increased and α-Toc was a major Toc isoform. Furthermore, to use chloroplast transformation to produce α-Toc-rich vegetable, TC-overexpressing transplastomic lettuce plants (pLTC) were generated. Total Toc levels and vitamin E activity increased in the pLTC plants compared with the wild-type lettuce plants. These findings indicated that chloroplast genetic engineering is useful to improve vitamin E quality and quantity in plants.