Cloning And Expression Analysis Of Zinc And Iron Transporter Gene ZIP From Nasturtium Officinale R. Br

ZRT, IRT-like protein (ZIP) is widespread in higher plants. They are a class of proteins which plays an important role in a variety of metal ion transport function. Most of its members have eight transmembrane domain structure. They play an important role in the transport of the metal ions from extracellular to intracellular and the transport process of metal ions in cells.Nasturtium officinale can growth in good condition under the environment of excessive heavy metal ions. They can absorb a large number of metal ions, but not harm the plant itself. Because of watercress has the characteristics of excessive absorption of heavy metal elements, it can be used to purify water quality. It can be used to explore the mechanism of phytoremediation.This paper cloned the conserved sequence fragment of NoZIP using the Nasturtium officinale root RNA as a template by two step method of RT-PCR. Primers were designed according to the conserved sequence of ZIP gene of rice, corn, wheat and other monocotyledonous angiosperm. Then through RACE (Rapid amplification of cDNA ends) method, this paper completed the cloning of NoZIP(Nasturtium officinale r. Br.ZRT, IRT-like protein, labeled NoZIP) gene. This gene full-length 1446bp, encoding a 357 amino acid residues of the peptide. It is speculated that the size of the peptide molecular weight 38.1 kDa, PI=6.49. Amino acid sequence and structure analysis showed that NoZIP contain nine relatively conservative transmembrane domain and four functional areas:Fe2+ transporters, Zn2+transporters, transport and binding protein (cationic and carrying iron compounds area), divalent metal ion transporters area (in inorganic ion transport and metabolism). Through the protein subcellular localization prediction, NoZIP contains signal peptide (SP) and the pathway of its synthesis and transport may be similar to secreted proteins. It may be a transmembrane channel protein which is located in the cell membrane. This paper shows that NoZIP and ZIP of other species amino acid sequence similarity was above 77% after BLAST analysis and phylogenetic tree construction. NoZIP and CbZIP have the highest similarityand have as high as 92% amino acid similarity with Pickpurse,This paper analyzed the NoZIP transcription level in Nasturtium officinale root and leaf in 6 different culture conditions. In the roots, the lack of both zinc ion and iron ion can induce gene expression. Nasturtium officinale root was more sensitive to iron deficiency. The expression of NoZIP gene in Nasturtium officinale is proportional to the degree Fe2+ and Zn2+ stress. In the leaf, both zinc ions and iron ion concentration can effect NoZIP gene transcription. Completely lack and no lack of zinc ions and iron ion both can’t induce gene transcription. NoZIP gene can transcript in Nasturtium officinale leaves only when the zinc or iron ions exist but under the condition of insufficient. This shows that the NoZIP gene has different expression patterns in the Nasturtium officinale’s leaves and roots.