title: Magnesium deficiency phenotypes upon multiple knockout of Arabidopsis thaliana MRS2 clade B genes can be ameliorated by concomitantly reduced calcium supply.
abstract: Plant MRS2 membrane protein family members have been shown to play important roles in magnesium uptake and homeostasis. Single and double knockouts for two Arabidopsis thaliana genes, AtMRS2-1 and AtMRS2-5, have previously not shown significant phenotypes even under limiting Mg(2+) supply although both are strongly expressed already in early seedlings. Together with AtMRS2-10, these genes form clade B of the AtMRS2 gene family. We now succeeded in obtaining homozygous AtMRS2-1/10 double and AtMRS2-1/5/10 triple knockout lines after selection under increased magnesium supply. Although wilting early, both new mutant lines develop fully and are also fertile under standard magnesium supply, but show severe developmental retardation under limiting Mg(2+) concentrations. To investigate nutrient dependency of germination and seedling development under various conditions, including variable supplies of Mg(2+), Ca(2+), Zn(2+), Mn(2+), Co(2+), Cd(2+) and Cu(2+), in a reproducible and economical way, we employed a small-scale liquid culturing system in 24-well plate set-ups. This allowed the growth and monitoring of individual plantlets of different mutant lines under several nutritional conditions in parallel, and the scoring and statistical evaluation of developmental stages and biomass accumulation. Detrimental effects of higher concentrations of these elements were similar in mutants and the wild type. However, growth retardation phenotypes seen upon hydroponic cultivation under low Mg(2+) could be ameliorated when Ca(2+) concentrations were concomitantly lowered, supporting indications for an important interplay of these two most abundant divalent cations in the nutrient homeostasis of plants.
authors: Abteilung Molekulare Evolution, IZMB-Institut für Zelluläre und Molekulare Botanik, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany.
authors: Henning
authors: H
authors: Lenz
authors: Vitalij
authors: V
authors: Dombinov
authors: Julia
authors: J
authors: Dreistein
authors: Martin R
authors: MR
authors: Reinhard
authors: Michael
authors: M
authors: Gebert
authors: Volker
authors: V
authors: Knoop
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D027682:Cation Transport Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D055786:Gene Knockout Techniques; D005838:Genotype; D018525:Germination / Q000187:drug effects / Q000235:genetics; D018527:Hydroponics; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D010641:Phenotype; D010802:Phylogeny; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D004269:DNA, Bacterial; C517535:MGT1 protein, Arabidopsis; C560261:MGT2 protein, Arabidopsis; C560262:MGT3 protein, Arabidopsis; C036483:T-DNA; D008274:Magnesium; D002118:Calcium
keywords: 2-TM-GxN proteins; Arabidopsis thaliana; Calcium; Hydroponic cultivation; Magnesium transport; Nutrient homeostasis