Questioning the role of salicylic acid and cytosolic acidification in mitogen-activated protein kinase activation induced by cryptogein in tobacco cells.
Elicitors of plant defence reactions, oligogalacturonides and cryptogein, an elicitin produced by Phytophthora cryptogea, were previously shown to induce a rapid and transient activation of two mitogen-activated protein kinases (MAPKs) in cells of tobacco [ Nicotiana tabacum L. cv. Xanthi; A. Lebrun-Garcia et al. (1998) Plant J 15:773-781]. We verified that these two MAPKs correspond to the salicylic acid-induced protein kinase (SIPK) and the wound-induced protein kinase (WIPK). The involvement of salicylic acid (SA) in cryptogein-induced MAPK activation was investigated using transgenic NahG tobacco cells expressing the salicylate hydroxylase gene and thus unable to accumulate SA. The large and sustained activation of both MAPKs by cryptogein was maintained in transgenic cells compared with non-transgenic tobacco cells. Moreover, weak acids, namely SA, 4-hydroxybenzoic acid, an ineffective analogue of SA in plant resistance, and butyric acid acidified the cytosol, a physiological event also induced by cryptogein, but activated both MAPKs only slightly and transiently in tobacco cells. These results indicate that MAPK activation by cryptogein is not mediated by SA, that cytosolic acidification can be transduced by MAPKs, and that in cryptogein-treated cells, cytosolic acidification should contribute poorly to MAPK activation.
Lebrun-Garcia
Angela
A
UMR INRA/Université de Bourgogne, Laboratoire de Biochimie, Biologie Cellulaire et Ecologie des Interactions Plantes/Micro-organismes, 17 Rue Sully, BP 86510, 21065 Dijon Cedex, France. lebrun@dijon.inra.fr
Chiltz
Annick
A
Gout
Elisabeth
E
Bligny
Richard
R
Pugin
Alain
A
D020418:Algal Proteins / Q000494:pharmacology*; D020148:Butyric Acid / Q000494:pharmacology; D002478:Cells, Cultured; D003600:Cytosol / Q000737:chemistry; D004789:Enzyme Activation / Q000187:drug effects; D005656:Fungal Proteins; D006863:Hydrogen-Ion Concentration; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics; D010226:Parabens / Q000494:pharmacology; D010940:Plant Proteins; D020156:Salicylic Acid / Q000494:pharmacology*; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*
D020418:Algal Proteins; D005656:Fungal Proteins; D010226:Parabens; D010940:Plant Proteins; C061032:cryptogein protein, Phytophthora cryptogea; D020148:Butyric Acid; D006899:Mixed Function Oxygenases; C022619:salicylate 1-monooxygenase; D020928:Mitogen-Activated Protein Kinases; C106405:SA-induced protein kinase; C113423:WIPK protein, Nicotiana tabacum; C038193:4-hydroxybenzoic acid; D020156:Salicylic Acid