Although magnesium(Mg) is one of the most important nutrients, involved in many enzyme activities and the structural stabilization of tissues, its importance as a macronutrient ion has been overlooked in recent decade...Although magnesium(Mg) is one of the most important nutrients, involved in many enzyme activities and the structural stabilization of tissues, its importance as a macronutrient ion has been overlooked in recent decades by botanists and agriculturists, who did not regard Mg deficiency(MGD) in plants as a severe health problem. However, recent studies have shown,surprisingly, that Mg contents in historical cereal seeds have markedly declined over time, and two thirds of people surveyed in developed countries received less than their minimum daily Mg requirement. Thus, the mechanisms of response to MGD and ways to increase Mg contents in plants are two urgent practical problems. In this review, we discuss several aspects of MGD in plants, including phenotypic and physiological changes, cell Mg2+homeostasis control by Mg2+transporters, MGD signaling, interactions between Mg2+and other ions, and roles of Mg2+in plant secondary metabolism. Our aim is to improve understanding of the influence of MGD on plant growth and development and to advance crop breeding for Mg enrichment.展开更多
Magnesium （Mg^2＋） is one of the essential cations in all cells. Although the Mg^2＋ transport mechanism has been well- documented in bacteria, less is known about Mg^2＋ transporters in eukaryotes. The AtMGT gene f...Magnesium （Mg^2＋） is one of the essential cations in all cells. Although the Mg^2＋ transport mechanism has been well- documented in bacteria, less is known about Mg^2＋ transporters in eukaryotes. The AtMGT gene family encoding putative magnesium transport proteins had been described previously. We report here that one of the Arabidopsis MGT family members, the AtMGT7 gene, encodes two mRNAs that have resulted from alternative splicing variants, designated AtMGT7a and AtMGT7b. Interestingly, the two mRNA variants were expressed with different patterns with AtMG77a expressing in all organs, but AtMGT7b appearing only in root and flowers. The AtMGT7a variant functionally complemented a bacterial mutant lacking Mg^2＋ transport capacity, whereas AtMGT7b did not. The 63Ni^2＋ tracer uptake analysis in the bacterial model showed that AtMGT7a mediated low-affinity transport of Mg^2＋. Consistent with the complementation assay result, 63Ni^2＋ tracer uptake analysis revealed that AtMGT7b did not transport Mg^2＋. This study therefore has identified from a higher plant the first low-affinity Mg^2＋ transporter encoded by a gene with alternatively spliced transcripts that produce proteins with distinct functions.展开更多
Aquaporins are important transmembrane water transport proteins which transport water and several neutral molecules. However, how aquaporins are involved in the synergistic transport of Mg2+and water remains poorly un...Aquaporins are important transmembrane water transport proteins which transport water and several neutral molecules. However, how aquaporins are involved in the synergistic transport of Mg2+and water remains poorly understood. Here, we found that the cassava aquaporin Me PIP2;7 was involved in Mg2+transport through interaction with Me MGT9, a lower affinity magnesium transporter protein. Knockdown of Me PIP2;7 in cassava led to magnesium deficiency in basal mature leaves with chlorosis and necrotic spots on their edges and starch over-accumulation. Mg2+content was significantly decreased in leaves and roots of Me PIP2;7-RNA interference(PIP-Ri) plants grown in both field and Mg2+-free hydroponic solution. Xenopus oocyte injection analysis verified that Me PIP2;7 possessed the ability to transport water only and Me MGT9 was responsible for Mg^(2+)effux.More importantly, Me PIP2;7 improved the transportability of Mg^(2+)via Me MGT9 as verified using the CM66 mutant complementation assay and Xenopus oocytes expressing system. Yeast twohybrid, bimolecular fuorescence complementation,co-localization, and co-immunoprecipitation assays demonstrated the direct protein–protein interaction between Me PIP2;7 and Me MGT9 in vivo. Mg2+fux was significantly elevated in Me PIP2;7-overexpressing lines in hydroponic solution through non-invasive micro-test technique analysis. Under Mg^(2+)-free condition, the retarded growth of PIP-Ri transgenic plants could be recovered with Mg^(2+)supplementation. Taken together, our results demonstrated the synergistic effect of the Me PIP2;7 and Me MGT9 interaction in regulating water and Mg2+absorption and transport in cassava.展开更多
基金supported by the Science Foundation of Zhejiang Sci-Tech University(grant 14042008-Y)the Zhejiang Provincial Natural Science Foundation of China(grant number LY13C130001)+1 种基金the Zhejiang Provincial Top Key Discipline of Biology(grant number 2012A03-C)the National Natural Science Foundation of China(grant number 81373908)
文摘Although magnesium(Mg) is one of the most important nutrients, involved in many enzyme activities and the structural stabilization of tissues, its importance as a macronutrient ion has been overlooked in recent decades by botanists and agriculturists, who did not regard Mg deficiency(MGD) in plants as a severe health problem. However, recent studies have shown,surprisingly, that Mg contents in historical cereal seeds have markedly declined over time, and two thirds of people surveyed in developed countries received less than their minimum daily Mg requirement. Thus, the mechanisms of response to MGD and ways to increase Mg contents in plants are two urgent practical problems. In this review, we discuss several aspects of MGD in plants, including phenotypic and physiological changes, cell Mg2+homeostasis control by Mg2+transporters, MGD signaling, interactions between Mg2+and other ions, and roles of Mg2+in plant secondary metabolism. Our aim is to improve understanding of the influence of MGD on plant growth and development and to advance crop breeding for Mg enrichment.
基金Supported by the National Natural Science Foundation of China (30370794)Hunan Provincial Natural Science Foundation for Excellent Youth Scholar (03JJY1003).
文摘Magnesium （Mg^2＋） is one of the essential cations in all cells. Although the Mg^2＋ transport mechanism has been well- documented in bacteria, less is known about Mg^2＋ transporters in eukaryotes. The AtMGT gene family encoding putative magnesium transport proteins had been described previously. We report here that one of the Arabidopsis MGT family members, the AtMGT7 gene, encodes two mRNAs that have resulted from alternative splicing variants, designated AtMGT7a and AtMGT7b. Interestingly, the two mRNA variants were expressed with different patterns with AtMG77a expressing in all organs, but AtMGT7b appearing only in root and flowers. The AtMGT7a variant functionally complemented a bacterial mutant lacking Mg^2＋ transport capacity, whereas AtMGT7b did not. The 63Ni^2＋ tracer uptake analysis in the bacterial model showed that AtMGT7a mediated low-affinity transport of Mg^2＋. Consistent with the complementation assay result, 63Ni^2＋ tracer uptake analysis revealed that AtMGT7b did not transport Mg^2＋. This study therefore has identified from a higher plant the first low-affinity Mg^2＋ transporter encoded by a gene with alternatively spliced transcripts that produce proteins with distinct functions.
基金supported by grants from the National Natural Science Foundation of China (31801417)Natural Science Foundation of Shanghai (17ZR1435200)+1 种基金the Open Project of State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources (SKLCUSA-b201703)the Earmarked Fund for China Agriculture Research System (CARS-11)。
文摘Aquaporins are important transmembrane water transport proteins which transport water and several neutral molecules. However, how aquaporins are involved in the synergistic transport of Mg2+and water remains poorly understood. Here, we found that the cassava aquaporin Me PIP2;7 was involved in Mg2+transport through interaction with Me MGT9, a lower affinity magnesium transporter protein. Knockdown of Me PIP2;7 in cassava led to magnesium deficiency in basal mature leaves with chlorosis and necrotic spots on their edges and starch over-accumulation. Mg2+content was significantly decreased in leaves and roots of Me PIP2;7-RNA interference(PIP-Ri) plants grown in both field and Mg2+-free hydroponic solution. Xenopus oocyte injection analysis verified that Me PIP2;7 possessed the ability to transport water only and Me MGT9 was responsible for Mg^(2+)effux.More importantly, Me PIP2;7 improved the transportability of Mg^(2+)via Me MGT9 as verified using the CM66 mutant complementation assay and Xenopus oocytes expressing system. Yeast twohybrid, bimolecular fuorescence complementation,co-localization, and co-immunoprecipitation assays demonstrated the direct protein–protein interaction between Me PIP2;7 and Me MGT9 in vivo. Mg2+fux was significantly elevated in Me PIP2;7-overexpressing lines in hydroponic solution through non-invasive micro-test technique analysis. Under Mg^(2+)-free condition, the retarded growth of PIP-Ri transgenic plants could be recovered with Mg^(2+)supplementation. Taken together, our results demonstrated the synergistic effect of the Me PIP2;7 and Me MGT9 interaction in regulating water and Mg2+absorption and transport in cassava.
