Metal transporter encoding gene families in Fabaceae: III. The zinc-iron permease (ZIP) gene family

Abstract

In plants, Zinc and Iron are transported through the membrane by proteins belonging to Zinc-Iron permease (ZIP: ZRT/IRT-like Protein). In this work, the ZIP gene families were identified in the genome of five legume species. The results demonstrated that the ZIPs were belonged to a multigeneic family in each species including soybean (28 genes), Medicago truncalata (16 genes), chickpea (7 genes), pigeon pea (12 genes), and Lotus japonicus (15 genes). Each gene contained from one to twelve introns. ZIP proteins possessed a conserved histidine-rich motif. Most of these proteins contained eight putative transmembrane domains and were predicted to be localized in plasma membranes. The phylogeny analysis showed that the legume ZIPs were classified into four main groups, each of which includes many subgroups. The group I contained the ZIP members of five examined plants. Moreover, the phylogeny showed gene gain events (expansion) in group I and gene loss events in other groups. The gene expansion in group I is likely to have arisen mainly from recent duplication events of ZIP genes in the examined legume plants, after specialization. The expression analysis showed that all of ZIP genes were expressed in all of the examined tissues in L. japonicus. The expression level of ZIP members was not similar in different tissues of the plant. Some ZIP genes were predominantly expressed in certain tissues for most of the legume species investigated.