title: The MAP kinase kinase MKK2 affects disease resistance in Arabidopsis.
abstract: The Arabidopsis mitogen-activated protein kinase (MAPK) kinase 2 (MKK2) was shown to mediate cold and salt stress responses through activation of the two MAP kinases MPK4 and MPK6. Transcriptome analysis of plants expressing constitutively active MKK2 (MKK2-EE plants) showed altered expression of genes induced by abiotic stresses but also a significant number of genes involved in defense responses. Both MPK4 and MPK6 became rapidly activated upon Pseudomonas syringae pv. tomato DC3000 infection and MKK2-EE plants showed enhanced levels of MPK4 activation. Although MKK2-EE plants shared enhanced expression of genes encoding enzymes of ethylene (ET) and jasmonic acid (JA) synthesis, ET, JA, and salicylic acid (SA) levels did not differ dramatically from those of wild-type or mkk2-null plants under ambient growth conditions. Upon P. syringae pv. tomato DC3000 infection, however, MKK2-EE plants showed reduced increases of JA and SA levels. These results indicate that MKK2 is involved in regulating hormone levels in response to pathogens. MKK2-EE plants were more resistant to infection by P. syringae pv. tomato DC3000 and Erwinia carotovora subsp. carotovora, but showed enhanced sensitivity to the fungal necrotroph Alternaria brassicicola. Our data indicate that MKK2 plays a role in abiotic stress tolerance and plant disease resistance.
authors.affiliation: Viikki Biocenter, Faculty of Biosciences, Department of Biological and Environmental Sciences, Division of Genetics, P.O. Box 56, FIN-00014 University of Helsinki, Finland.
authors.forename: Günter
authors.initials: G
authors.lastname: Brader
authors.forename: Armin
authors.initials: A
authors.lastname: Djamei
authors.forename: Markus
authors.initials: M
authors.lastname: Teige
authors.forename: E Tapio
authors.initials: ET
authors.lastname: Palva
authors.forename: Heribert
authors.initials: H
authors.lastname: Hirt
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001203:Ascomycota / Q000254:growth & development; D003517:Cyclopentanes / Q000378:metabolism; D044084:Erwinia amylovora / Q000254:growth & development; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D054883:Oxylipins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D030821:Plants, Genetically Modified; D044224:Pseudomonas syringae / Q000254:growth & development; D020156:Salicylic Acid / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; C011006:jasmonic acid; C036216:ethylene; C488959:MKK2 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases; D020156:Salicylic Acid