title: Overexpression of wound-responsive RNA-binding  proteins induces leaf senescence and hypersensitive-like  cell death.
abstract: Leaf senescence is a form of programmed cell death, and involves regulated expression of a specific set of senescence-associated genes (SAGs). In Arabidopsis, three UBA2 genes, UBA2a, UBA2b, and UBA2c, encode heterogeneous nuclear ribonucleoprotein (hnRNP)-type RNA-binding proteins. Previously, it has been demonstrated that expression of UBA2 genes is induced by mechanical wounding in a splice variant-dependent manner. Constitutive overexpression of the UBA2 genes proved lethal. Accordingly, a conditional gain-of-function system was used here to assess phenotypes related to UBA2 overexpression. Overexpression of each of the three UBA2 genes leads to a leaf yellowing/cell death-like phenotype in Arabidopsis plants. Expression levels of a number of SAGs, such as SAG13, SAG14, SAG15, SAG101, WRKY6, WRKY53, WRKY70, ACS2, ACS6, CML38 and SIRK, were elevated upon induction of UBA2 overexpression, as were transcripts of multiple wounding- and defense-related genes, including EDS1, CK1, JR1, WR3 and MPK3. Elevated ethylene biosynthesis and hypersensitive-like patterns of cell death and callose deposition, shown by Trypan blue and aniline blue staining, respectively, were also observed following induced overexpression of UBA2a, UBA2b, and UBA2c. These results indicate that induction of UBA2 gene expression stimulates leaf yellowing and cell death phenotypes through senescence and defense response pathways.
authors.affiliation: Biology Department, Penn State University, 208 Mueller Laboratory, University Park, PA 16802, USA.|Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Cha Young
authors.initials: CY
authors.lastname: Kim
authors.affiliation: Biology Department, Penn State University, 208 Mueller Laboratory, University Park, PA 16802, USA.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Bove
authors.affiliation: Biology Department, Penn State University, 208 Mueller Laboratory, University Park, PA 16802, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Assmann
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology; D002467:Cell Nucleus / Q000737:chemistry; D016922:Cellular Senescence / Q000235:genetics*; D005030:Ethylenes / Q000096:biosynthesis; D005936:Glucans / Q000378:metabolism; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D005030:Ethylenes; D005936:Glucans; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C531400:UBA2a protein, Arabidopsis; C531401:UBA2b protein, Arabidopsis; C531402:UBA2c protein, Arabidopsis; C048306:callose; C036216:ethylene