ArabidopsisTransporter MGT6 Mediates Magnesium Uptake and Is Required for Growth under Magnesium Limitation

Abstract

Although magnesium (Mg 2+ ) is the most abundant divalent cation in plant cells, little is known about the mechanism of Mg 2+ uptake by plant roots. Here, we report a key function of Magnesium Transport6 (MGT6)/Mitochondrial RNA Splicing2-4 in Mg 2+ uptake and low-Mg 2+ tolerance in Arabidopsis thaliana. MGT6 is expressed mainly in plant aerial tissues when Mg 2+ levels are high in the soil or growth medium. Its expression is highly induced in the roots during Mg 2+ deficiency, suggesting a role for MGT6 in response to the low-Mg 2+ status in roots. Silencing of MGT6 in transgenic plants by RNA interference (RNAi) resulted in growth retardation under the low-Mg 2+ condition, and the phenotype was restored to normal growth after RNAi plants were transferred to Mg 2+ -sufficient medium. RNAi plants contained lower levels of Mg 2+ compared with wild-type plants under low Mg 2+ but not under Mg 2+ -sufficient conditions. Further analysis indicated that MGT6 was localized in the plasma membrane and played a key role in Mg 2+ uptake by roots under Mg 2+ limitation. We conclude that MGT6 mediates Mg 2+ uptake in roots and is required for plant adaptation to a low-Mg 2+ environment.

Magnesium stress signaling in plant: Just a beginning

“…10 Although little change in the expression levels of these MgTRs were observed in microarray analysis when the plants were under MgSs, [8][9][10] results obtained from real time PCR detection showed significant changes for many MgTRs, for example AtMGT6 responding to Mg starvation. 30 We recently found that 8 AtMGTs and AtMHX were responding to MgT 1 and the findings were consistent with results obtained from serpentine conditions, where 6 MgTRs were highly expressed in the mesophyll and some could be correlated with higher accumulation of Mg in plants. 34 These indicate that most of MgTRs are more sensitive to MgT than to MgD.…”

“…Moreover, the importance of these genes and transporters could be verified from their diverse subcellular localization, for instance, in plasma membrane, endoplasmic reticulum, vacuole, mitochondria, and chloroplast. 27,30 However, only AtMGT6, were discovered in responding to Mg starvation. The dwarf phenotypes of the later 2 mutants under MgD treatments could be ameliorated with lowering Ca 2C concentration, 33 indicating the role of these transporters in Ca 2C and Mg 2C homeostasis in cells.…”

A Magnesium Transporter OsMGT1 Plays a Critical Role in Salt Tolerance in Rice

“…There are 10 MGT homologs in the Arabidopsis genome and nine homologs in rice (Schock et al, 2000;Gebert et al, 2009). Among them, AtMGT6 in Arabidopsis and OsMGT1 in rice mediate root Mg uptake, respectively, although they differ in their gene expression patterns (Mao et al, 2014;Chen et al, 2012). In this study, we found that OsMGT1 is involved in enhancing OsHKT1;5 transport activity at least in rice.…”

Two Distinct Families of Protein Kinases Are Required for Plant Growth under High External Mg2+ Concentrations in Arabidopsis

“…Therefore, it is essential for photosynthesis. Recent studies have revealed that several mitochondrial RNA splicing2 (MRS2)/magnesium transport (MGT) proteins, which are structurally homologous to bacterial Co 2+ resistance A (CorA) proteins and ALUMINUM RESISTANCE1 (ALR1), ALR2, and MRS2 in yeast, play an important role in Mg 2+ transport and plant growth under low external Mg 2+ conditions (Gebert et al, 2009;Lenz et al, 2013;Mao et al, 2014). However, it remains largely unknown how plants maintain cellular Mg 2+ homeostasis under high external Mg 2+ conditions.…”