Stacking Nicotianamine Synthase and ferritin genes to increase the iron content of rice endosperm
2013
Balindong, J. | Trijatmiko, K.R. | Torrizo, L. | Malabanan, P. B. | Borja, Ma.G. | Manzanilla, M. | Chadha-Mohanty, P. | Dionisio-Sese, M. | Mendioro, M. | Barry, G. | Slamet-Loedin, I.
Iron deficiency is the most common and widespread nutritional problem in the world. In the Philippines, its prevalence is highest among infants 6-11 months old (55.70%) with about 42.5% of pregnant women being afflicted (FNRI 2008). Biofertification provides a truly feasible means of reaching malnourished populations in relatively remote rural areas. This strategy will be used to develop staple food crops that, in some sense, fortify themselves. Genetic modification, together with conventional breeding, is a combined strategy to improve iron content in milled rice. Nicrotianamine (NA) is a metal chelator present ubiquitously in higher plants. It chelates iron for intercellular transport in the phloem and is a critical transporter in the delivery of mineral nutrients to developing seeds. The authors over expressed the nicotianamine synthase gene (OS NAS) under constitutive promoter in high-iron breeding line IR69428 and developed another set of transgenic events harboring the ferritin gene from soybean under the control of an endosperm-specific promoter, GluB1. Four homozygous events containing a single ferritin gene with three fold iron content were crossed to pyramid the transgenes. A total of 59 F1 plants were obtained and its seeds were grown. The presence of the two transgenes was confirmed through PCR [polymerase chain reaction] in the F2 plants, and iron content in the seed endosperm from this generation was analyzed through histochemical staining and inductive couple plasma spectrophotometry. Three selected F2 events showed more intense stain toward the endosperm and exhibited an increase of about five to six fold iron content as compared with wild type content.
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