Analysis of IR64 marker free transgenic ferritin for iron fortification
2010
Duenas, C. | Poletti, S. | Oliva, N. | Manzanilla, M. | Torrizo, L. | Zhou, W. | Shou, X. | Chadha-Mohanty, C. | Barry, G. | Slamet-Loedin, I., International Rice Research Inst., DAPO Box 7777, Metro Manila (Philippines). Plant Breeding, Genetic and Biotechnology Div.
Rice constitutes up to 80% of the daily caloric intake for people in developing countries yet the polished grain contains low levels of iron (Fe) and zinc (Zn). Because of this, iron deficiency is most prevalent in developing countries. Ferritin is a storage form of iron in plants and is the most common dietary iron, which can store up to 4500 Fe (111) atoms in its cavity in soluble and bioavailable form. Consequently, increasing the iron storage capacity in the endosperm by over-expression of ferritin is a strategy to increase the iron content in rice seeds. It has been demonstrated that iron from soybean ferritin is equal in bioavailability to FeSO4 (Lonnerdal, et al., 2006) and a number of reports have shown that the iron content of a polished grain can be significantly increased by expressing the soybean ferritin gene in the endosperm (Gato, et al. 1999, Qu et al. 2005); however, this is the first ferritin study in rice of using a mega variety and marker free transformation. In this study, the authors evaluated the marker free progeny lines expressing ferritin genes from soybean (soyfer NH1) under the control of rice endosperm specific glutelin promoter, co-transformed with a separate Agrobacterium vector containing hygromycin marker gene (5:1 ratio). Expression of ferritin protein of T1 and T2 homozygous lines was determined by ELISA and in situ tissue hybridization. A 5-10 fold expression of soyfer NH1 protein in transgenic events compared to IR64 controlled was obtained. The iron content was quantified by colorimetric and ICP.
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