Increasing iron content of IR64 by overexpression of nicotianamine synthase (OsNAS) and soybean ferritin gene (Soyfer no. 1)
2012
Trijatmiko, K.R. | Due�as, C.N. Jr. | Oliva, N. | Torrizao, L. | Manzanilla, M. | Borja, Ma.G. | Chadha-Mohanty, P. | Barry, G. | Slamet-Leodin, I., International Rice Research Inst., DAPO 7777, Metro Manila (Philippines
Increasing iron content in polished rice could provide a low-cost sustainably strategy to remedy iron deficiency affecting more than 2 billion inhabitants of the world's population. A large number of transgenic events of IR64 megavariety harboring a nicotianamine synthase (OsNAS) gene under control of 35S promoter and a ferritin (Soyfer No.1) gene under control of an endosperm specific promoter were produced through Agrobacterium-mediated transformation. High iron events were selected based on color intensity after Perl Prussian blue seed staining and subjected to Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) for iron content determination. Results showed increase in iron content up to 9 folds (19ppm) in the milled rice as compared to IR64 control (2-3ppm). Events that had an increase in iron beyond 4 folds were further analyzed for copy number using DNA blot analysis. The presence of beyond T-DNA border sequence integration was evaluated by flanking sequence analysis of insertion site identified using inverse PCR method. The authors identified transgenic events of IR64 showing 11 ppm iron content with single copy of both genes and without beyond T-DNA border transfer. It suggests that over expression of transporter genes and increasing storage protein in polished grains open the possibility to reach 30% Estimated Average Requirement (EAR) of dietary iron in staple food.
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