SOSPECT Project

Salinity represents the 2nd most important abiotic stress (after drought) causing huge economic losses in the world including European Mediterranean countries. The Na+ ion is the main cause of salt stress for plants. It is thus important to characterize determinants of plant salt tolerance, particularly in crops sensitive to salt like rice, in a context of reduction of agricultural surfaces and increasing soil salinization. The ability of plant to tolerate salinity requires the Na+/H+ antiporter SOS1 of the Salt Overly Sensitive (SOS) pathway. This transporter redirects excess Na+ ions to the apoplast. Its role in apoplastic pH regulation is unknown. Evidence is emerging that pectin, a cell wall polysaccharide, is a major player in mitigating the deleterious effects of salinity but the mechanisms remain elusive. Pectin Remodeling Enzymes (PREs) such as pectin- methylesterase (PME, EC 3.1.1.11) and - acetylesterase (PAE, EC 3.1.1.6) as well as ions within the cell wall and its pH, can modulate the pectin structure with subsequent effects on cell wall mechanical properties. The SOSPECT project aims at investigating in two species, Arabidopsis and rice, displaying different contents of pectins, how ion distribution including pH in the cell wall influences the pectin structure and hence the cell wall integrity of root cells under a short and long salt stress exposure. Using a range of multidisciplinary approaches including ion transport activity (SOS1, H+ pump) and PRE activity mutants, cell wall ion distribution (NanoSIMS, ionselective microelectrodes, fluorescent pH sensors) and binding abilities, cell wall biochemistry, pectin imaging (3D Storm nanoscopy), cell wall mechanics (FluidFM) and phenotyping (Phenobox/Rhizobox) of salt tolerance, the SOSPECT project, divided into 4 work packages (WP), will generate an integrated model showing the interrelation between ion transport activities and ion distribution in the wall and cell wall properties for plant salt tolerance.

The management of the SOSPECT projet will be done by Catherine RAYON (P1, UPJV, UMRT INRAE ,1158 -BEA-BioPI). Two additional partners will constitute the consortium : Anne-Aliénor VERY (P2), UMR 5004 CNRS-INRAE-SupAgro-Université Montpellier, will involve, as a subcontractant, Alexis PEAUCELLE (CR INRAE, Institut Jean-Pierre Bourgin, UMR1318, INRAE-AgroParisTech; Dirk SCHAUMLÖFFEL (P3), UMR 5254 IPREM CNRS-Université de Pau et des Pays de l’Adour.