Zinc is an essential micronutrient for plant growth and development.The deficiency and excess of Zn is harmful to plants.In plants,CDF (cation diffusion facilitator proteins) also known as metal tolerance proteins (metal tolerance protein,MTP) can transport Zn to vacuole,thus regulate the absorption and translocation of Zn in plants.In current work,a zinc transporter of CDF family MtMTP3 was identified in model plant Medicago truncatula.The results of bioinformatics analyses showed that MtMTP3 encoded 385 amino acids.The results of phylogenetic analysis and sequence alignment showed that MtMTP3 is belonged to zinc transporter of CDF family.Expressing of MtMTP3 in yeast increased the resistance of yeast to zinc.The results of expression analysis showed that MtMTP3 was mainly expressed in root.When growing at high concentration of zinc,manganese or iron deficiency condition,the expression of MtMTP3 were increased in root,indicating that MtMTP3 may function as metal transporter in root.The results of semiquantitative RT-PCR showed that the expression of MtMTP3 were significantly increased under low P condition.The expression of MtMTP3 were decreased when it was inoculated AMF,even in high Zn condition.It is indicated that mycorrhiza may decrease the expression of MtMTP3 via enhancing the absorption of phosphate.