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Caractérisation du canal mécanosensible RMA et recherche de sa contribution à la mécanotransduction racinaire chez Arabidopsis thaliana

Abstract : The plant plasma membrane is subjected to mechanical stress generated by the turgor pressure, the development of the adjacent tissues or external mechanical cues such as wind. Transmembrane proteins, called mechanosensitive channels, permeate ions through the membrane when activated by an increase in the membrane mechanical tension. These nanosensors of mechanical cues directly transduce changes in tension into electrical potential variation, rapidly triggering cell mechanotransduction signaling pathways. The activity of a native mechanosensitive channel permeating calcium was recently recorded at the plasma membrane of the model plant Arabidopsis thaliana with the patch-clamp technique. This mechanosensitive channel, which is dependent on the DEK1 protein, is still not identified and was called Rapid Mechanically Activated (RMA). In the context of this PhD, the dynamics of gating of the RMA mechanosensitive channel were characterised over time and pressure and an activation model was proposed. Moreover, mutant plants knocked-out for genes encoding putative calcium mechanosensitive channels (Piezo, OSCAs) were analysed in order to find out its molecular identity. In parallel, the involvement of RMA in mechanically-induced calcium signaling in roots was investigated using the calcium sensor R-GECO expressed in Arabidopsis seedlings. These seedlings were grown in microponic chips in such way that their root grew in a channel of controlled liquid medium and controlled flow. Roots were subjected either to osmotic shock or to squeezing and calcium signals were recorded. The link between the observations obtained at the molecular and the root scales is discussed in order to give an integrated view of the function of RMA mechanosensitive channel.
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Yannick Guerringue. Caractérisation du canal mécanosensible RMA et recherche de sa contribution à la mécanotransduction racinaire chez Arabidopsis thaliana. Biologie végétale. Université Paris-Saclay, 2020. Français. ⟨NNT : 2020UPASS105⟩. ⟨tel-02927435⟩

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