Maize is an important food and forage crop worldwide.In developing countries maize is a staple food to provide micro-nutrients,such as zinc and iron,for people living in rural areas.Understanding the uptake,transport and accumulation mechanism of essential nutrients in maize is of primary importance for improving the nutritional quality of this crop.The zinc-regulated transporters,iron-regulated transporter-like protein (ZIP) transporter is responsible for uptake and transport of divalent metal ion.ZmZIP5,identified in our lab previously,could complement the yeast growth defect of zinc and iron double mutants,and localized to the both endoplasmic reticulum and plasma membrane.In the present report,the GUS activity of ZmZIP5-promoter-GUS transgenic plants was observed in germinated seeds,young sheath,and stem.ZmZIP5 constitutively overexpression (OXZmZIP5) and RNAi (ZmZIP5i) lines were generated.At the seedling stage,the zinc and iron contents were all increased in roots and shoots of overexpression lines while that were all decreased in RNAi lines.Unexpected,the zinc and iron contents in seeds of OXZmZIP5 and ZmZIP5i lines were decreased and unchanged,respectively ly.In order to enhance Zn/Fe contents in seeds,endosperm specific ZmZIP5 overexpression lines were generated and both zinc and iron were increased in grains.These results indicate that ZmZIP5 is responsible for the uptake and root-to-shoot translocation of Zn/Fe.Endosperm-specific overexpressing ZmZIP5 could increase the zinc and iron contents in maize grains.The present study provides new insights into the role of ZIP genes in zinc and iron biofortification of cereal grains.