title: Regulation of floral organ abscission in Arabidopsis thaliana.
abstract: Abscission is a developmental program that results in the active shedding of infected or nonfunctional organs from a plant body. Here, we establish a signaling pathway that controls abscission in Arabidopsis thaliana from ligand, to receptors, to downstream effectors. Loss of function mutations in Inflorescence Deficient in Abscission (IDA), which encodes a predicted secreted small protein, the receptor-like protein kinases HAESA (HAE) and HAESA-like 2 (HSL2), the Mitogen-Activated Protein Kinase Kinase 4 (MKK4) and MKK5, and a dominant-negative form of Mitogen-Activated Protein Kinase 6 (MPK6) in a mpk3 mutant background all have abscission-defective phenotypes. Conversely, expression of constitutively active MKKs rescues the abscission-defective phenotype of hae hsl2 and ida plants. Additionally, in hae hsl2 and ida plants, MAP kinase activity is reduced in the receptacle, the part of the stem that holds the floral organs. Plants overexpressing IDA in a hae hsl2 background have abscission defects, indicating HAE and HSL2 are epistatic to IDA. Taken together, these results suggest that the sequential action of IDA, HAE and HSL2, and a MAP kinase cascade regulates the programmed separation of cells in the abscission zone.
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Sung Ki
authors.initials: SK
authors.lastname: Cho
authors.forename: Clayton T
authors.initials: CT
authors.lastname: Larue
authors.forename: David
authors.initials: D
authors.lastname: Chevalier
authors.forename: Huachun
authors.initials: H
authors.lastname: Wang
authors.forename: Tsung-Luo
authors.initials: TL
authors.lastname: Jinn
authors.forename: Shuqun
authors.initials: S
authors.lastname: Zhang
authors.forename: John C
authors.initials: JC
authors.lastname: Walker
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D020935:MAP Kinase Signaling System; D009154:Mutation; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins