Activation of a mitogen-activated protein kinase pathway is involved in disease resistance in tobacco.
Hypersensitive response (HR), a form of programmed cell death, is frequently associated with plant disease resistance. It has been proposed that mitogen-activated protein kinase (MAPK) cascades regulate HR cell death based on pharmacological studies by using kinase inhibitors. However, direct evidence is lacking. Here, we demonstrate that NtMEK2, a MAPK kinase, is upstream of salicylic acid-induced protein kinase (SIPK) and wounding-induced protein kinase (WIPK), two tobacco MAPKs that are activated by various pathogens or pathogen-derived elicitors. Expression of a constitutively active mutant of NtMEK2 induces HR-like cell death in tobacco, which is preceded by the activation of endogenous SIPK and WIPK. In addition, NtMEK2-SIPK/WIPK cascade appears to control the expression of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) and l-phenylalanine ammonia lyase (PAL), two defense genes encoding key enzymes in the phytoalexin and salicylic acid biosynthesis pathways. These results demonstrate that a plant MAPK cascade controls multiple defense responses against pathogen invasion.
Yang
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KY
Department of Biochemistry, University of Missouri-Columbia, 117 Schweitzer Hall, Columbia, MO 65211, USA.
Liu
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Zhang
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D016960:Agrobacterium tumefaciens / Q000235:genetics; D020418:Algal Proteins; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000502:physiology*; D017360:Arabidopsis / Q000235:genetics; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D003907:Dexamethasone / Q000494:pharmacology; D005656:Fungal Proteins / Q000633:toxicity; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000502:physiology; D007113:Immunity, Innate / Q000235:genetics; D048370:MAP Kinase Kinase 2; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D008969:Molecular Sequence Data; D010650:Phenylalanine Ammonia-Lyase / Q000502:physiology; D010935:Plant Diseases / Q000235:genetics*; D018515:Plant Leaves; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D010947:Plants, Toxic; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D014170:Transformation, Genetic; D019076:Transgenes
D020418:Algal Proteins; D005656:Fungal Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C061032:cryptogein protein, Phytophthora cryptogea; D003907:Dexamethasone; D006903:Hydroxymethylglutaryl CoA Reductases; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; C106405:SA-induced protein kinase; C113423:WIPK protein, Nicotiana tabacum; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases; D010650:Phenylalanine Ammonia-Lyase