Improving iron content in polished rice seeds through rice nicotianamine synthase 2 (OsNas2) expression
2015
Bueno, G.M. | Arines, F.M. | Tsakirpaloglou, N. | Trijatmiko, K.R. | Arcillas, E. | Manzanilla, M. | Borja, Ma.G. | Torrizo, L. | Slamet-Loedin, I.
Iron deficiency is among the predominant micro nutrient deficiencies, especially in developing countries, affecting approximately two billion people and causing more than 0.8 million deaths annually. Biofortification comprises a sustainable approach for micronutrient alleviation. With this, increased concentration of micronutrients in edible portions of crops can be achieved through conventional breeding of genetic engineering. In rice, several transgenic approaches have been utilized so far to increase the iron (Fe) concentration of rice grains (Slamet-Leodin et al; 2015). Selection of appropriate promoter is considered important as it determines the specificity and regulates the level of transgene expression. Here, the expression pattern of Oryza sativa thioredoxin promoter (pOsTRX) was determined through in silico analysis using Rice Expresscin Profile Database (RiceXPro) and BETA-glucoronidase (GUS) reporter gene histochemical analysis. Both analysis indicated extensive expression in leaf blade, leaf sheath, root, anther, and ovary. pOSTRX suitability in increasing the Fe content of polished rice grains when combined with Oryza sativa nicotianamine synthase 2 (OsNAS2) was determined as well. Inductively Coupled Plasma by Optical Emission Spectrometry (ICP-OES) analysis indicated that single-copy polished rice grains of pOsTRX::OsNAS2 combination resulted up to 9.5 ppm Fe compared to the wild type (WT) counterpart (0.71 ppm Fe). Additionally, agronomic traits such as plant height, panicle number, filled grain number, and grain yield of selected T1 transgenic lines over expressing OsNAS2 were not significantly different from WT. Thus, recent progress in understanding the efficiency of pOsTRX could offer an alternative approach to provide high-iron rice.
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