Ectopic expression of apple fruit homogentisate phytyltransferase gene (MdHPT1) increases tocopherol in transgenic tomato (Solanum lycopersicum cv. Micro-Tom) leaves and fruits.
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 T(1) 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 T(1) 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.
Department of Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Young Sam
YS
Seo
Soo Jin
SJ
Kim
Chee Hark
CH
Harn
Woo Taek
WT
Kim
D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D027845:Malus / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D024502:alpha-Tocopherol / Q000032:analysis* / Q000378:metabolism
D029681:Arabidopsis Proteins; D019883:Alkyl and Aryl Transferases; C446531:HPT1 protein, Arabidopsis; C412723:phytyltransferase; D024502:alpha-Tocopherol