title: AM fungal exudates activate MAP kinases in plant cells in dependence from cytosolic Ca(2+) increase.
abstract: The molecular dialogue occurring prior to direct contact between the fungal and plant partners of arbuscular-mycorrhizal (AM) symbioses begins with the release of fungal elicitors, so far only partially identified chemically, which can activate specific signaling pathways in the host plant. We show here that the activation of MAPK is also induced by exudates of germinating spores of Gigaspora margarita in cultured cells of the non-leguminous species tobacco (Nicotiana tabacum), as well as in those of the model legume Lotus japonicus. MAPK activity peaked about 15 min after the exposure of the host cells to the fungal exudates (FE). FE were also responsible for a rapid and transient increase in free cytosolic Ca(2+) in Nicotiana plumbaginifolia and tobacco cells, and pre-treatment with a Ca(2+)-channel blocker (La(3+)) showed that in these cells, MAPK activation was dependent on the cytosolic Ca(2+) increase. A partial dependence of MAPK activity on the common Sym pathway could be demonstrated for a cell line of L. japonicus defective for LjSym4 and hence unable to establish an AM symbiosis. Our results show that MAPK activation is triggered by an FE-induced cytosolic Ca(2+) transient, and that a Sym genetic determinant acts to modulate the intensity and duration of this activity.
authors.affiliation: DiVaPRA, Patologia Vegetale, Università degli Studi di Torino, Via L. da Vinci, 44, 10095 Grugliasco (TO), Italy.
authors.forename: Doriana
authors.initials: D
authors.lastname: Francia
authors.forename: Annick
authors.initials: A
authors.lastname: Chiltz
authors.forename: Fiorella
authors.initials: F
authors.lastname: Lo Schiavo
authors.forename: Alain
authors.initials: A
authors.lastname: Pugin
authors.forename: Paola
authors.initials: P
authors.lastname: Bonfante
authors.forename: Francesca
authors.initials: F
authors.lastname: Cardinale
mesh_terms: D045424:Complex Mixtures / Q000737:chemistry / Q000494:pharmacology*; D055137:Glomeromycota / Q000737:chemistry* / Q000502:physiology; D000070116:Lotus / Q000166:cytology / Q000201:enzymology*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D059828:Plant Cells / Q000201:enzymology*; D010940:Plant Proteins / Q000378:metabolism*; D013172:Spores, Fungal / Q000737:chemistry / Q000378:metabolism; D013559:Symbiosis / Q000502:physiology; D013997:Time Factors; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology*
chemical_list: D045424:Complex Mixtures; D010940:Plant Proteins; D020929:Mitogen-Activated Protein Kinase Kinases