Iowa State Generates Pro-Vitamin A Rich GM Maize

Transgenic approaches were successful in enhancing the levels of pro-vitamin A in maize kernels. A group of researchers at Iowa State University reports that the transgenic maize they have developed using the Hi-II germplasm  can produce high levels of provitamin A comparable to 50% of the US Institute of Medicine Estimated Average Requirement.

The maize lines were transformed by overexpressing the bacterial crtB and crtI genes in an endosperm-specific manner, using a modified and highly active -zein promoter. The researchers attribute the increase in the total carotenoids from the overexpression of the crtB (for phytoene synthase) and crtI (for the four desaturation steps of the carotenoid pathway catalysed by phytoene desaturase and -carotene desaturase in plants).  The levels of carotenoid attained (up to 34-fold) were found to be reproducible over at least four generations. Nutritionists have estimated a goal of 15 µg provitamin A g^–1 dry weight of kernel, the Iowa State GM maize came very close with 13.6 µg g^–1 of provitamin A g^–1 dry weight kernel. 

The open access article published by the Journal of Experimental Botany can be found at http://jxb.oxfordjournals.org/cgi/content/abstract/ern212v1?ct=ct