Magnesium uptake characteristics in Arabidopsis revealed by 28Mg tracer studies
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The Mg2+ uptake system in Arabidopsis roots is Gd3+- and Fe2+-sensitive, and responds to a changing Mg2+ concentration within 1 h with the participation of AtMRS2 transporters.
Magnesium (Mg2+) absorption and the mechanism regulating its activity have not been clarified yet. To address these issues, it is necessary to reveal the characteristics of Mg2+ uptake in roots. Therefore, we first investigated the Mg2+ uptake characteristics in roots of 1-week-old Arabidopsis plants using 28Mg. The Mg2+ uptake system in roots was up-regulated within 1 h in response to the low Mg2+ condition. This induction was inhibited in Arabidopsis “mitochondrial RNA splicing 2/magnesium transport” mutants atmrs2-4/atmgt6 and atmrs2-7/atmgt7, while the expression of AtMRS2-4/AtMGT6 and AtMRS2-7/AtMGT7 genes in the Arabidopsis wild-type was not responsive to Mg2+ conditions. In addition, the Mg deficiency-induced Mg2+ uptake system was shut-down within 5 min when Mg2+ was resupplied to the environment. An inhibition study showed that the constitutive mechanism functioning in Mg2+ uptake under Mg2+ sufficient conditions was sensitive to a number of divalent and trivalent cations, particularly Gd3+ and Fe2+, but not to K+.
KeywordsAbiotic stress CorA/MRS2 family Inhibitor Mg deficiency Radionuclide Root
Hexammine cobalt(III) chloride
Mitochondrial RNA splicing 2
Authors thank Dr. Martin O’Brien for English editing. This work was partially supported by JSPS KAKENHI Grant-in-Aid for Young Scientists (B) (number 17K15236), JSPS KAKENHI Grant-in-Aid for Scientific Research (A) (15H02469) and JST PROSTO (number JPMJPR15Q7). This work was also sponsored by JSPS and F.R.S.-FNRS under the Japan - Belgium Research Cooperative Programme.
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