Magnesium Homeostasis in Plants

Leher, Siegfried (2022) Magnesium Homeostasis in Plants. Doctoral thesis, University of East Anglia.

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Magnesium (Mg2+) is an essential nutrient for all life on earth. Mg2+ is required for the activity of a large number of enzymes, as well as for the structure of DNA, RNA, proteins and biological membranes. Mg2+ is also necessary for the activity of adenosine triphosphate (ATP) and is especially important for reactions producing and consuming this energy-currency. Despite the downstream symptoms of Mg2+-deficiency (MgD) within plants being relatively well-known, knowledge about the initial symptoms of MgD, plant perception of MgD and regulatory mechanisms involved is lacking. This project therefore aims to elucidate the symptoms of and responses to MgD, using both forward and reverse genetic approaches.

A high-throughput method of inducing MgD was established and compared to methods used previously. In conjunction with the genetically-encoded, ratiometric sensors ATeam 1.03-nD/nA and pHusion, this method was used to show that levels of the Mg2+-ATP-complex, as well as cytoplasmic and apoplastic pH, increase in leaves of Arabidopsis seedlings under MgD. An alternative model of the events occurring during MgD was generated. Additionally, the Mg2+-sensitive FRET-sensor MARIO was functionally expressed in A. thaliana.

The MRS2-family makes up the most important family of Mg2+-specific transport proteins in plants, but knowledge around their subcellular localisation and regulatory mechanisms is incomplete. Fluorescently-tagged expression constructs were used to provide additional data on the subcellular localisation and functional relevance of the family members MRS2-3 and MRS2-4.

RNA-sequencing on A. thaliana exposed to MgD was used to find potential MgD reporter genes. Transcriptional MgD reporter plants were generated and used to carry out a forward genetic screen with the aim of finding genes involved in the response to MgD. Putative Mg2+-mutants were identified. Although mutant phenotypes could not be unambiguously attributed to individual mutations, lists of genetic variants potentially causative of mutant phenotypes are given.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 28 Sep 2022 13:42
Last Modified: 31 Mar 2023 01:38


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