title: Regulation of leaf senescence by NTL9-mediated osmotic stress signaling in Arabidopsis.
abstract: Leaf senescence is a highly regulated genetic process that constitutes the last stage of plant development and provides adaptive fitness by relocating metabolites from senescing leaves to reproducing seeds. Characterization of various senescence mutants, mostly in Arabidopsis, and genome-wide analyses of gene expression, have identified a wide array of regulatory components, including transcription factors and enzymes as well as signaling molecules mediating growth hormones and environmental stress responses. In this work we demonstrate that a membrane-associated NAC transcription factor, NTL9, mediates osmotic stress signaling in leaf senescence. The NTL9 gene is induced by osmotic stress. Furthermore, activation of the dormant, membrane-associated NTL9 is elevated under the same conditions. A series of senescence-associated genes (SAGs) were upregulated in transgenic plants overexpressing an activated form of NTL9, and some of them were slightly but reproducibly downregulated in a T-DNA insertional NTL9 knockout mutant. These observations indicate that NTL9 mediates osmotic stress responses that affect leaf senescence, providing a genetic link between intrinsic genetic programs and external signals in the control of leaf senescence.
authors.affiliation: Molecular Signaling Laboratory, Department of Chemistry, Seoul National University, Seoul 151-742, Korea.
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Yoon
authors.forename: Sang-Gyu
authors.initials: SG
authors.lastname: Kim
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Chung-Mo
authors.initials: CM
authors.lastname: Park
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; C531121:NTL9 protein, Arabidopsis; D014157:Transcription Factors