Vitamin E Shown to Accumulate in GM Potato Tubers

Vitamin E or tocopherol, is important for human health. The compound is only synthesized by photosynthetic organisms. Researchers in the United States have investigated the biosynthesis of this essential compound in potato tubers, an underground, non-photosynthetic tissue. Their study reports the first investigation of vitamin E biosynthesis in a non-photosynthetic tissue and the first attempt to elevate vitamin E levels in potato tubers.

Elizabeth Crowell and colleagues used the Agrobacterium method to transform the potato varieties ‘Spunta’ and ‘MSE149-5Y’. The researchers employed high-performance liquid chromatography to determine the expression levels of the Arabidopsis genes that were incorporated into the potato varieties. The transgenes used were the Arabidopsis thaliana p-hydroxyphenylpyruvate dioxygenase (At-HPPD) and A. thaliana homogentisate phytyltransferase (At-HPT).

Crowell and colleagues have observed that over-expression of At-HPPD resulted in a maximum 266% increase in alpha-tocopherol while over-expression of At-HPT resulted in a 106% increase. The accumulated amount of tocopherol however is still 10- and 100-fold less than the level of tocopherol in the potato leaves or seeds, respectively. The researchers suspect that physiological and regulatory constraints may be limiting the accumulation of tocopherol in potato tubers.

For more information and to access the full article in the journal Transgenic Research, please visit http://www.springerlink.com/content/g0515325830j8m74/.