Characterization of a Glomus intraradices gene encoding a putative Zn transporter of the cation diffusion facilitator family

A full-length cDNA (GintZnT1) encoding a putative Zn transporter was isolated from the extraradical mycelium of Glomus intraradices. Based on its sequence analysis, GintZnT1 was classified as a member of the cation diffusion facilitator (CDF) family of heavy metal transporters. Functional analysis of GintZnT1 was performed by heterologous expression in yeast mutants defective in different CDFs. Although Zn sensitivity of the mutants was not reverted, an effect of GintZnT1 on the labile regulatory Zn pool was detected by using a Zn-regulated β-galactosidase reporter gene. GintZnT1 expression was studied in the extraradical mycelium obtained from a symbiotic root organ culture. Gin ± ZnT1 was up-regulated in the extraradical mycelium of G. intraradices upon short-time exposure to Zn and when the mycelia were developed in 75 μM Zn supplemented plates. These data suggest a role of GintZnT1 in Zn compartmentalization and in the protection of G. intraradices against Zn stress.