Four plasma membrane-localized MGR transporters mediate xylem Mg2+ loading for root-to-shoot Mg2+ translocation in Arabidopsis

Meng, Su-Fang; Zhang, Bin; Tang, Rachel; Zheng, Xinglong; Chen, Rui; Liu, Congge; Jing, Yanping; Ge, Hui‐Ming; Zhang, Chi; Chu, Yanli; Fu, Aigen; Zhao, Fugeng; Luan, Sheng

doi:10.1016/j.molp.2022.01.011

Cited by 18 publications

(21 citation statements)

References 45 publications

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“…Mg 2+ is transported from roots to aerial tissues by MGR transporters for photosynthesis [37,38]. Long-term MD triggers dramatic molecular responses in plants including microtubulebased movement, signal transduction, protein phosphorylation and regulation of light harvesting, and the photosynthesis antioxidant system [39,40].…”

Section: Discussionmentioning

confidence: 99%

Chlorophyll decomposition is accelerated in banana leaves after the long-term magnesium deficiency according to transcriptome analysis

Kan

Yang

et al. 2022

PLoS ONE

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Magnesium (Mg) is an essential macronutrient for plant growth and development. Physiological and transcriptome analyses were conducted to elucidate the adaptive mechanisms to long-term Mg deficiency (MD) in banana seedlings at the 6-leaf stage. Banana seedlings were irrigated with a Mg-free nutrient solution for 42 days, and a mock control was treated with an optimum Mg supply. Leaf edge chlorosis was observed on the 9th leaf, which gradually turned yellow from the edge to the interior region. Accordingly, the total chlorophyll content was reduced by 47.1%, 47.4%, and 53.8% in the interior, center and edge regions, respectively, and the net photosynthetic rate was significantly decreased in the 9th leaf. Transcriptome analysis revealed that MD induced 9,314, 7,425 and 5,716 differentially expressed genes (DEGs) in the interior, center and edge regions, respectively. Of these, the chlorophyll metabolism pathway was preferentially enriched according to Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The expression levels of the five candidate genes in leaves were consistent with what is expected during chlorophyll metabolism. Our results suggest that changes in the expression of genes related to chlorophyll synthesis and decomposition result in the yellowing of banana seedling leaves, and these results are helpful for understanding the banana response mechanism to long-term MD.

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Section: Discussionmentioning

confidence: 99%

Chlorophyll decomposition is accelerated in banana leaves after the long-term magnesium deficiency according to transcriptome analysis

Kan

Yang

et al. 2022

PLoS ONE

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“…The lack of any one of these transporters significantly reduces the above-ground content of the ions that the transporter was carrying (Gaymard et al, 1998; Nieves-Cordones et al, 2010; Sasaki et al, 2012; Ueno et al, 2015). In case of Mg 2+ , the fact that xylem Mg 2+ loading is mediated by the efflux-type transporters in Arabidopsis (Meng et al, 2022) suggests the systems for uptake and translocation are distinct. We thought that if it was the Mg 2+ influx function that was directly impaired in LMGC1, and the reduction in Mg 2+ transport to the shoot was a secondary effect, then the reduction in influx would have occurred prior to the reduction in Mg 2+ translocation.…”

Section: Discussionmentioning

confidence: 99%

“…The concentration of Mg 2+ in rice xylem sap is concentrated compared to the external solution when the Mg 2+ concentration of the external solution is less than 3 mM (Tanoi et al, 2011). In Arabidopsis, MGR4 and MGR6 are responsible in this mechanism as xylem loaders in the root stele (Meng et al, 2022) and MTP10 acts as a xylem unloader in the shoot parenchyma cells in vascular bundles (Ge et al, 2022). Mutations in these transporters cause modification in Mg content in the whole plant.…”

Section: Introductionmentioning

confidence: 99%

Mutations in OsRZF1, encoding a zinc-finger protein, causes reduced magnesium uptake in roots and translocation to shoots in rice

Kobayashi

Takagi

Yang

et al. 2022

Preprint

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Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of about 3,000 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. The MutMap method identified 7.4 kbp deletion in the LMGC1 genome leading to a loss of two genes. Genome editing using CRISPR-Cas9 further revealed that one of the two lost genes, a gene belonging to RanBP2-type zinc finger family, was the causal gene of the low-Mg phenotype. Considering this gene, named OsRZF1, has never been reported to be involved in ion transport, the phenotype of LMGC1 would be associated with a novel mechanism of Mg homeostasis in plants.

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“…In search of Mg transporters that function in Mg sequestration into the vacuole, we identified plant Mg 2+ transporters homologous to the ACDP/CNNM family, which are referred to as the Magnesium Release (MGR) family (Tang et al ., 2022). The Arabidopsis MGR family consists of nine members divided into three clades (clade I–clade III) based on phylogenetic analysis and their subcellular localizations (Meng et al ., 2022; Tang et al ., 2022). While the three members in clade I function in vacuolar Mg sequestration and four members in clade II mediate xylem Mg 2+ loading for root‐to‐shoot Mg 2+ translocation (Meng et al ., 2022; Tang et al ., 2022), the function of other members remains unknown.…”

Section: Introductionmentioning

confidence: 99%

“…The Arabidopsis MGR family consists of nine members divided into three clades (clade I–clade III) based on phylogenetic analysis and their subcellular localizations (Meng et al ., 2022; Tang et al ., 2022). While the three members in clade I function in vacuolar Mg sequestration and four members in clade II mediate xylem Mg 2+ loading for root‐to‐shoot Mg 2+ translocation (Meng et al ., 2022; Tang et al ., 2022), the function of other members remains unknown. In the present study, we focus on the functional characterization of the two members in clade III, MGR8 and MGR9, that we show here are localized to the chloroplast inner envelope.…”

Section: Introductionmentioning

confidence: 99%

Two magnesium transporters in the chloroplast inner envelope essential for thylakoid biogenesis in Arabidopsis

Zhang

Tang

et al. 2022

New Phytologist

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Magnesium (Mg 2+ ) serves as a cofactor for a number of photosynthetic enzymes in the chloroplast, and is the central atom of the Chl molecule. However, little is known about the molecular mechanism of Mg 2+ transport across the chloroplast envelope.Here, we report the functional characterization of two transport proteins in Arabidopsis: Magnesium Release 8 (MGR8) and MGR9, of the ACDP/CNNM family, which is evolutionarily conserved across all lineages of living organisms.Both MGR8 and MGR9 genes were expressed ubiquitously, and their encoded proteins were localized in the inner envelope of chloroplasts. Mutations of MGR8 and MGR9 together, but neither of them alone, resulted in albino ovules and chlorotic seedlings. Further analysis revealed severe defects in thylakoid biogenesis and assembly of photosynthetic complexes in the double mutant. Both MGR8 and MGR9 functionally complemented the growth of the Salmonella typhimurium mutant strain MM281, which lacks Mg 2+ uptake capacity. The embryonic and early seedling defects of the mgr8/mgr9 double mutant were rescued by the expression of MGR9 under the embryo-specific ABI3 promoter. The partially rescued mutant plants were hypersensitive to Mg 2+ deficient conditions and contained less Mg 2+ in their chloroplasts than wild-type plants.Taken together, we conclude that MGR8 and MGR9 serve as Mg 2+ transporters and are responsible for chloroplast Mg 2+ uptake.

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Four plasma membrane-localized MGR transporters mediate xylem Mg2+ loading for root-to-shoot Mg2+ translocation in Arabidopsis

Cited by 18 publications

References 45 publications

Chlorophyll decomposition is accelerated in banana leaves after the long-term magnesium deficiency according to transcriptome analysis

Chlorophyll decomposition is accelerated in banana leaves after the long-term magnesium deficiency according to transcriptome analysis

Mutations in OsRZF1, encoding a zinc-finger protein, causes reduced magnesium uptake in roots and translocation to shoots in rice

Two magnesium transporters in the chloroplast inner envelope essential for thylakoid biogenesis in Arabidopsis

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