Role of heterotrimeric G protein β subunit during root endosymbioses

Dangeville, Pierre (2022) Role of heterotrimeric G protein β subunit during root endosymbioses. Doctoral thesis, University of East Anglia.

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Abstract

Root endosymbiosis is formed with nitrogen-fixing bacteria and phosphate-delivering arbuscular mycorrhizal fungi. These endosymbionts colonize the root cell intracellular space of their host to trade nutrients in exchange for photosynthetic-derived carbon source. Prior to root colonization, specific chemical communication between the two partners is required to establish a root endosymbiotic interaction. Recognition by the host of bacterial or fungal symbiotic elicitors results similarly in induction of nuclear calcium oscillations essential for transcriptional reprograming and induction of symbiotic genes. But the transducing signal that activates nuclear calcium signalling in this pathway is unknown. Heterotrimeric G protein β subunit (Gβ) has been previously shown to positively regulate root endosymbiosis with nitrogen-fixing bacteria in three legumes. We hypothesised that Gβ functions in transducing signal during root endosymbioses. Loss-of-function of Medicago truncatula Gβ confirmed its positive role during association with symbiotic bacteria. Characterization of several MtGβ mutants with missense mutations allowed us to identify several amino acid residues critical for its function. Live-cell imaging following application of symbiotic elicitors enabled us to determine its role during activation of nuclear calcium signalling. Furthermore, we identified a protein target of MtGβ that together may control root endosymbioses. This study investigates the role of the MtGβ in transducing signals during root endosymbiosis, confirming its positive regulatory function and identifying critical amino acid residues and a potential protein target involved in this process.

Keywords: Root legume symbioses, nuclear calcium signalling, heterotrimeric G protein β subunit.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	26 Oct 2023 09:48
Last Modified:	26 Oct 2023 09:48
URI:	https://ueaeprints.uea.ac.uk/id/eprint/93478
DOI:

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