Homogentisate phytyltransferase (HPT) is an important enzyme in the biosynthesis of tocopherols (vitamin E). Herein, an HPT homolog (MdHPT1) was isolated from apple (Malus domestica Borkh. cv. Fuji) fruits, whose gene expression level gradually decreased during fruit ripening, reaching a background level in ripened apple fruits. The amounts of α- and γ-tocopherols, two major tocopherols in plant organs, were 5- to 14-fold lower in the fruits than in the leaves and flowers of apple plants. Transgenic tomato plants (Solanum lycopersicum cv. Micro-Tom) overexpressing MdHPT1 were next constructed. Transgenic independent T1 leaves contained ∼1.8- to 3.6-fold and ∼1.6- to 2.9-fold higher levels of α-tocopherol and γ-tocopherol, respectively, than those in control plants. In addition, the levels of α-tocopherol and γ-tocopherol in 35S:MdHPT1 T1 fruits increased up to 1.7-fold and 3.1-fold, respectively, as compared to the control fruits, indicating that an increase in α-tocopherol in fruits (maximal 1.7-fold) was less evident than that in leaves (maximal 3.6-fold). This finding suggests that the apple MdHPT1 plays a role in tocopherol production in transgenic tomatoes.
Bibliographical noteFunding Information:
We are thankful to Dr. Myung Hee Nam and Ms. Joo Hee Chung at the Korea Basic Science Institute (Seoul, Korea) for their help and discussion about tocopherol analysis. This work was supported by grants from the BioGreen 21 Program (funded by the Rural Development Administration ), the Technology Development Program for Agriculture and Forestry (Project No. 309017-5 funded by the Ministry for Agriculture, Forestry and Fisheries, Republic of Korea ), and the National Research Foundation (Project No. 2009-0078317 funded by the Ministry of Education, Science, and Technology, Republic of Korea ).
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Plant Science