title: An arabidopsis mitogen-activated protein kinase cascade, MKK9-MPK6, plays a role in leaf senescence.
abstract: Leaf senescence is a developmentally programmed cell death process that constitutes the final step of leaf development, and it can be regulated by multiple environmental cues and endogenous signals. The mitogen-activated protein kinase (MAPK) cascades play diverse roles in intracellular and extracellular signaling in plants. Roles of the MAPK signaling module in leaf senescence are unknown. Here, a MAPK cascade involving MKK9-MPK6 is shown to play an important role in regulating leaf senescence in Arabidopsis (Arabidopsis thaliana). Both MKK9 and MPK6 possess kinase activities, with MPK6 an immediate target of MKK9, as revealed by in vitro, in vivo, and in planta assays. The constitutive and inducible overexpression of MKK9 causes premature senescence in leaves and in whole Arabidopsis plants. The premature senescence phenotype is suppressed when MKK9 is overexpressed in the mpk6 null background. When either MKK9 or MPK6 is knocked out, leaf senescence is delayed.
authors.affiliation: Department of Horticulture, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Chunjiang
authors.initials: C
authors.lastname: Zhou
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Cai
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Guo
authors.forename: Susheng
authors.initials: S
authors.lastname: Gan
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016922:Cellular Senescence; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000166:cytology / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; C527379:MKK9 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases