Overexpression of barley nicotianamine synthase gene, HvNAS1, improved iron and zinc concentrations in rice seeds

Abstract

In humans, Iron (Fe) and Zinc (Zn) deficiencies are serious problems around the world. Transgenic approaches will be a breakthrough to produce Fe- and Zn-fortified rice varieties to improve human health. Nicotianamine (NA) chelates Fe²⁺ and Zn²⁺ and plays a critical role in plant body to transport these metals to sink tissues including seeds. We aimed to increase Fe and Zn concentrations in rice seeds by overexpressing barley NA synthase gene, HvNAS1, under the control of rice Actin promoter. NA concentrations were significantly increased in shoots of transgenic rice lines than those of non transgenic rice. Fe and Zn concentrations in polished T₁ seeds of transgenic rice lines also increased more than 3 and 2 times respectively. Fe and Zn concentrations in roots and shoots were not significantly increased. These results suggest that translocation of Fe and Zn into seeds is enhanced by overproduction of NA.