Iron and zinc biofortification of rice by synergistic expression of OsNAS2 gene with monocot (Pennisetum glaucum) and dicot (Phaseolus vulgaris) ferritins

Iron and zinc deficiencies are the most prevalent cause of global hidden hunger. Rice, being one of the most consumed crops worldwide, is suitable to target for Fe and Zn biofortification. In present study, we generated rice transgenic lines to meet the recommended dietary requirement of iron and zinc through endosperm specific expression of dicot (kidney bean) and monocot (pearl millet) Ferritins along with constitutive expression of rice nicotianamine synthase 2 (OsNAS2) gene. Visualization through perls' prussian staining and quantification by ICP-MS showed significant improvement in grain iron content in all the transgenic lines. The transgenic lines expressing any of the three selected gene combinations (PvFerrtin-OsNAS2, feedPgFerrtin-OsNAS2 and foodPg-Ferritin-OsNAS2), showed the potential to surpass the 30% of the estimated average requirement (13 mu g/g Fe and 28 mu g/g Zn) proposed for rice in HarvestPlus breeding program. Though the expression of PvFerritin along with OsNAS2 gene in IET10364 (indica) variety showed the best result, providing up to 4.2-and 3.5-fold increase in iron (30.56 mu g/g) and zinc (60.1 mu g/g) content, respectively; in polished grains compared to non-transgenic control. Thus, the lines developed in our study can be used for further breeding purpose to enhance the iron and zinc content in commercial rice varieties.

Automated summary

Iron and zinc deficiencies are common causes of hidden hunger globally. This study successfully enhanced the iron and zinc content in rice through transgenic techniques. The expression of dicot and monocot Ferritins along with OsNAS2 gene significantly improved grain iron content. The developed transgenic lines have the potential to meet the recommended dietary requirement for rice.