The Role of Root-Specific Expression of ZIP Genes in The Control of Zn and Cd Translocation to Shoots

Presented research contributes to understanding contribution of tobacco ZIP family (ZRT-IRT –like Proteins) in the regulation of the efficiency of Zn/Cd translocation to shoots, which depends on combinations of Zn/Cd concentrations in the medium. Previous study indicated the role of differential expression of NtZIP1 and NtZIP4 in roots [1]. Current research focused on NtZIP4, and to lesser extend on other tobacco ZIPs. The role of the apical and basal root segments was taken into account.

The NtZIP4 was cloned. Transient expression of the fusion constructs 35S::NtZIP4::GFP in tobacco leaves demonstrated their localization to the plasmamembrane. Expression of NtZIP4 in wild-type yeasts and in the zrt1zrt2 mutant showed that Zn and Cd are substrates for the protein. The real-time-qPCR and expression of NtZIP4p::GUS in tobacco showed that expression of NtZIP4 was expressed equally in both root segments, however several other ZIPs were differentially expressed in the apical and basal part of the root. Moreover, it was shown that NtZIP4 was expressed in the central cylinder and in the pericycle, but not in the epidermis. Thus it does not contribute to the uptake of Zn and Cd directly from the medium. The accumulation of Zn and Cd in apical and basal root parts, as well as expression of tobacco ZIPs, depended on the combinations on medium Zn/Cd concentrations indicating possible distinct role of tested root segments in the regulation of Zn/Cd dependent translocation of metals to shoots.

[1] Barabasz et al, JExpBot. 2016, 67,6201-6214

Acknowledgement: The research was carried out within the OPUS 8 project no. 2014/15/B/NZ9/02303, financially supported by the NCN, Poland.