title: Gα modulates salt-induced cellular senescence and cell division in rice and maize.
abstract: The plant G-protein network, comprising Gα, Gβ, and Gγ core subunits, regulates development, senses sugar, and mediates biotic and abiotic stress responses. Here, we report G-protein signalling in the salt stress response using two crop models, rice and maize. Loss-of-function mutations in the corresponding genes encoding the Gα subunit attenuate growth inhibition and cellular senescence caused by sodium chloride (NaCl). Gα null mutations conferred reduced leaf senescence, chlorophyll degradation, and cytoplasm electrolyte leakage under NaCl stress. Sodium accumulated in both wild-type and Gα-mutant shoots to the same levels, suggesting that Gα signalling controls cell death in leaves rather than sodium exclusion in roots. Growth inhibition is probably initiated by osmotic change around root cells, because KCl and MgSO4 also suppressed seedling growth equally as well as NaCl. NaCl lowered rates of cell division and elongation in the wild-type leaf sheath to the level of the Gα-null mutants; however there was no NaCl-induced decrease in cell division in the Gα mutant, implying that the osmotic phase of salt stress suppresses cell proliferation through the inhibition of Gα-coupled signalling. These results reveal two distinct functions of Gα in NaCl stress in these grasses: attenuation of leaf senescence caused by sodium toxicity in leaves, and cell cycle regulation by osmotic/ionic stress.
authors.affiliation: Department of Biology at the University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Urano
authors.affiliation: Department of Biology at the University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Colaneri
authors.affiliation: Department of Biology at the University of North Carolina, Chapel Hill, NC, 27599-3280, USA Department of Pharmacology at the University of North Carolina, Chapel Hill, NC, 27599-3280, USA alan_jones@unc.edu.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Jones
mesh_terms: D018533:Biomass; D002455:Cell Division / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects*; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism*; D017353:Gene Deletion; D017343:Genes, Plant; D007477:Ions; D008954:Models, Biological; D009154:Mutation; D012275:Oryza / Q000166:cytology* / Q000187:drug effects / Q000235:genetics; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D010940:Plant Proteins / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics; D036226:Seedlings / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D003313:Zea mays / Q000166:cytology* / Q000187:drug effects / Q000235:genetics
chemical_list: D044385:GTP-Binding Protein alpha Subunits; D007477:Ions; D010940:Plant Proteins; D012965:Sodium Chloride
keywords: Abiotic stress; NaCl stress; maize; plant heterotrimeric G protein; rice; sodium perception.