Magnesium Transporter MGT6 Plays an Essential Role in Maintaining Magnesium Homeostasis and Regulating High Magnesium Tolerance in Arabidopsis.

ABSTRACT: Magnesium (Mg) is one of the essential nutrients for all living organisms. Plants acquire Mg from the environment and distribute within their bodies in the ionic form via Mg²⁺-permeable transporters. In Arabidopsis, the plasma membrane-localized magnesium transporter MGT6 mediates Mg²⁺ uptake under Mg-limited conditions, and therefore is important for the plant adaptation to low-Mg environment. In this study, we further assessed the physiological function of MGT6 using a knockout T-DNA insertional mutant allele. We found that MGT6 was required for normal plant growth during various developmental stages when the environmental Mg²⁺ was low. Interestingly, in addition to the hypersensitivity to Mg²⁺ limitation, mgt6 mutants displayed dramatic growth defects when external Mg²⁺ was in excess. Compared with wild-type plants, mgt6 mutants generally contained less Mg²⁺ under both low and high external Mg²⁺ conditions. Reciprocal grafting experiments further underpinned a role of MGT6 in a shoot-based mechanism for detoxifying excessive Mg²⁺ in the environment. Moreover, we found that mgt6 mgt7 double mutant showed more severe phenotypes compared with single mutants under both low- and high-Mg²⁺ stress conditions, suggesting that these two MGT-type transporters play an additive role in controlling plant Mg²⁺ homeostasis under a wide range of external Mg²⁺ concentrations.

SUBMITTER: Yan YW 

PROVIDER: S-EPMC5857585 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature