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Insight on the regulation of calcium-signaling in response to magnesium deficiency in Arabidopsis thaliana

par Wathar, Charlotte
Promoteur Verbruggen, Nathalie
Co-Promoteur Webb, Alex A. A. R.
Publication Non publié, 2022-09-06

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Résumé :

Mg2+ is a macronutrient playing an essential role for plants and any other form of life, including humans. Today, Mg2+ deficiency (Mg-D) in soils is an increasingly worrying problem, which limits crop yields and affects human nutrition. The role of Mg2+ and the effects of Mg-D in plants have been widely described. However, very little is known about Mg-D sensing and signaling. Recent lines of evidence points to an important role of Ca2+ in the Mg-D response and as a potential secondary messenger in a Mg-D signaling pathway. One of these lines of evidence came from an RNA-seq analysis performed at the ULB host laboratory to identify early transcripts alterations under Mg-D. In this experiment, the functional category of Ca2+-binding proteins (CaBPs) was overrepresented, emphasizing the potential role of Ca2+-signaling under Mg-D.In this master thesis, we firstly aimed to describe these new Ca2+-related actors involved in the Mg-D response of Arabidopsis thaliana. We confirmed the early differential expression of some of these CaBPs (CPK10, CPK27, CPK29, CML46, CML47, CML49, CAM9 and CMI1) by RT-qPCR. With the exception of CAM9 which was repressed under Mg-D, all other genes were strongly upregulated. To investigate the role of some of these CaBPs, we phenotyped their mutants (cpk10, cpk27 and cpk29) during Mg-D by measuring rosette and root growth-related parameters. The mutant cpk27.1 showed no significant reduction in growth under Mg-D, while growth of the wild-type plants was significantly reduced. The other mutants were not different from the WT, possibly due to a redundancy of function between these CaBPs.Second, this master thesis aimed to explore indirectly whether changes in Mg2+ status affected the well-known [Ca2+]cyt signature in response to several stimuli using aequorin-based luminescence targeted to the cytosol of Arabidopsis thaliana. For all the different Mg2+ conditions tested (Mg-D and Mg2+-excess), only the amplitude of the [Ca2+]cyt signature in response to these stimuli was altered with respect to Mg2+-sufficiency. Mg2+-sufficient plants showed an intermediate response between the two other Mg2+ conditions resulting in a positive or negative correlation between Mg2+ status and the amplitude of the [Ca2+]cyt signature.In conclusion, this master thesis highlights that Ca2+ has an important role in plant response to Mg-D and provides further indirect evidence on its likely role as a secondary messenger in signaling Mg-D.