The maize CorA/MRS2/MGT-type Mg transporter, ZmMGT10, responses to magnesium deficiency and confers low magnesium tolerance in transgenic Arabidopsis

Abstract

ZmMGT10 was specifically expressed in maize roots and induced by a deficiency of magnesium. Overexpression of ZmMGT10 restored growth deficiency of the Salmonella typhimurium MM281 strain and enhanced the tolerance in Arabidopsis to stress induced by low magnesium levels by increasing uptake of Mg via roots. CorA/MRS2/MGT-type Mg transporters play a significant role in maintaining magnesium (Mg) homeostasis in plants. Although the maize CorA/MRS2/MGT family comprises of 12 members, currently no member has been functionally characterized. Here, we report the isolation and functional characterization of ZmMGT10 from the maize MRS2/MGT gene family. ZmMGT10 has a typical structure feature which includes two conserved TMs near the C-terminal end and an altered AMN tripeptide motif. The high sequence similarity and close phylogenetic relationship indicates that ZmMGT10 is probably the counterpart of Arabidopsis AtMGT6. The complementation of the Salmonella typhimurium mutated MM281 strain indicates that ZmMGT10 possesses the ability to transport Mg. ZmMGT10 was specifically expressed in the plant roots and it can be stimulated by a deficiency of Mg. Transgenic Arabidopsis plants which overexpressed ZmMGT10 grew more vigorously than wild-type plants under low Mg conditions, exhibited by longer root length, higher plant fresh weight and chlorophyll content, suggesting ZmMGT10 was essential for plant growth and development under low Mg conditions. Further investigations found that high accumulation of Mg occurred in transgenic plants attributed to improved Mg uptake and thereby enhanced tolerance to Mg deficiency. Results from this investigation illustrate that ZmMGT10 is a Mg transporter of maize which can enhance the tolerance to Mg deficient conditions by improving Mg uptake in the transgenic plants of Arabidopsis.

The molecular–physiological functions of mineral macronutrients and their consequences for deficiency symptoms in plants

“…The double mutant mgt6 mgt7 showed more severe phenotypes compared with single mutants under both low‐ and high‐Mg conditions, indicating that these two MGT‐type transporters play additive roles in controlling plant Mg 2+ homeostasis under a wide range of external Mg concentrations (Yan et al ., 2018). Transgenic A. thaliana plants overexpressing ZmMGT10 exhibited longer root length, higher shoot weight, chlorophyll content and Mg 2+ uptake under low Mg conditions, thus suggesting that ZmMGT10 is essential for plant growth and development (H. Li et al ., 2017).…”

Short-Term Magnesium Deficiency Triggers Nutrient Retranslocation in Arabidopsis thaliana

“…The induction of root Mg 2+ uptake is characterised in Arabidopsis (Ogura et al, 2018) and rice (Tanoi et al, 2014), and Mg 2+ transporter family MITOCHONDRIA RNA SPLICING 2/MAGNESIUM TRANSPORTER (MRS2/MGT; Schock et al, 2000;Li et al, 2001) is indicated to be putatively responsible (Mao et al, 2014;Ogura et al, 2018). However, there is uncertainty regarding the root transcriptional regulation of MRS2/MGT genes with some reports suggesting that Mg deficiency induces root transcript levels of MRS2/MGT (Mao et al, 2014;Li et al, 2017;Liu et al, 2019) and others suggesting no transcriptional induction of MRS2/MGT (Gebert et al, 2009;Hermans et al, 2010a,b;Ogura et al, 2018).…”

Comparative genomics revealed the gene evolution and functional divergence of magnesium transporter families in Saccharum

“…In Oryza sativa , OsMGT1 was found to play an important role in the tolerance to Al toxicity and salt stress [23]. In maize, ZmMGT10 is essential in response to Mg deficiency, and confers low Mg tolerance when the ZmMGT10 gene is overexpressed in Arabidopsis thaliana [24].…”