Cloning and Biological Function of the Three ZIP Transporters in Blueberry

The growth and metabolism of blueberry were greatly affected by the balance of metal ions. ZIP transporter protein family played a key role in regulating the metal homeostasis in plants. However, there were few studies on ZIP transporter protein in blueberry. In order to explore the absorption and transport mechanism of ZIP transporter protein gene in blueberry to the metal ions, such as ferric ion (Fe), zinc (Zn), cadmium (Cd), the members of ZIP gene family in blueberry were cloned by using the northern highbush blueberry Brigitta as the research material. The nucleotide sequence, amino acid sequence and transmembrane domain of the candidate genes were obtained by using the bioinformatics method. Compared with the ZIP family genes of other plants, the phylogenetic tree was constructed and the key research objects with high similarity were screened. The biological function of ZIP transporters in blueberry was explored by analyzing the expression of VcZIPs gene in blueberry with metal hydroponics. The function of heterologous expression of VcZIPs was verified by carrying out the metal tolerance analysis test of transgenic yeast. The results showed that: eight full-length cDNA sequences of VcZIPs were cloned, among which the three transporters, including VcZIP4, VcZIP7 and VcZIP9 had the typical secondary structure of the ZIP family or were the potential members of the ZIP family. The results of qRT-PCR showed that the gene transcription level of ZIP transporter in the leaves of blueberry was generally inhibited by the excessive metal ions. The expression of VcZIPs genes in the roots of blueberry was generally induced by the excessive metal ions in rhizosphere. The expression level of VcZIP4 gene was up-regulated by 5.3, 86.5, and 45.4 times compared with the control (CK) in the deficient Fe, excessive Fe and excessive Cd treatment groups, respectively. The expression level of VcZIP7 gene was up-regulated by 27.2 times compared with the control in the excessive Fe treatment group. The expression level of VcZIP9 gene was the most significant under the conditions of excessive Fe and excessive Cd treatments, which was up-regulated by 142.8 times and 360.2 times compared with the control (CK), respectively. The metal tolerance analysis of transgenic yeast showed that, VcZIP7 might have the function of cadmium transport. Both VcZIP4 and VcZIP9 could mediate the transport of manganese, while VcZIP7 didn't have the ability to transport manganese. VcZIP4, VcZIP7 and VcZIP9 all had the function of iron transport, among which VcZIP7 had the highest function of iron transport, and its relatively low expression might be an important reason for the low efficiency of iron nutrition of blueberry. The results could lay a foundation for revealing the transportation mechanism of the ZIP metal transporter family of blueberry.