title: NEVERSHED and INFLORESCENCE DEFICIENT IN ABSCISSION are differentially required for cell expansion and cell separation during floral organ abscission in Arabidopsis thaliana.
abstract: Floral organ shedding is a cell separation event preceded by cell-wall loosening and generally accompanied by cell expansion. Mutations in NEVERSHED (NEV) or INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) block floral organ abscission in Arabidopsis thaliana. NEV encodes an ADP-ribosylation factor GTPase-activating protein, and cells of nev mutant flowers display membrane-trafficking defects. IDA encodes a secreted peptide that signals through the receptor-like kinases HAESA (HAE) and HAESA-LIKE2 (HSL2). Analyses of single and double mutants revealed unique features of the nev and ida phenotypes. Cell-wall loosening was delayed in ida flowers. In contrast, nev and nev ida mutants displayed ectopic enlargement of abscission zone (AZ) cells, indicating that cell expansion alone is not sufficient to trigger organ loss. These results suggest that NEV initially prevents precocious cell expansion but is later integral for cell separation. IDA is involved primarily in the final cell separation step. A mutation in KNOTTED-LIKE FROM ARABIDOPSIS THALIANA1 (KNAT1), a suppressor of the ida mutant, could not rescue the abscission defects of nev mutant flowers, indicating that NEV-dependent activity downstream of KNAT1 is required. Transcriptional profiling of mutant AZs identified gene clusters regulated by IDA-HAE/HSL2. Several genes were more strongly downregulated in nev-7 compared with ida and hae hsl2 mutants, consistent with the rapid inhibition of organ loosening in nev mutants, and the overlapping roles of NEV and IDA in cell separation. A model of the crosstalk between the IDA signalling pathway and NEV-mediated membrane traffic during floral organ abscission is presented.
authors: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors: Bin
authors: B
authors: Liu
authors: Melinka A
authors: MA
authors: Butenko
authors: Chun-Lin
authors: CL
authors: Shi
authors: Jenny L
authors: JL
authors: Bolivar
authors: Per
authors: P
authors: Winge
authors: Grethe-Elisabeth
authors: GE
authors: Stenvik
authors: Ane Kjersti
authors: AK
authors: Vie
authors: Michelle E
authors: ME
authors: Leslie
authors: Tore
authors: T
authors: Brembu
authors: Wenche
authors: W
authors: Kristiansen
authors: Atle M
authors: AM
authors: Bones
authors: Sara E
authors: SE
authors: Patterson
authors: Sarah J
authors: SJ
authors: Liljegren
authors: Reidunn B
authors: RB
authors: Aalen
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D049109:Cell Proliferation; D002473:Cell Wall / Q000378:metabolism; D015536:Down-Regulation; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D056626:Inflorescence / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D030821:Plants, Genetically Modified; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D020690:GTPase-Activating Proteins; C512213:IDA protein, Arabidopsis; C544765:NEV protein, Arabidopsis; D010455:Peptides
keywords: ARF-GAP; cell wall degradation; cell wall loosening; cell-to-cell communication; petal breakstrength; scanning electron microscopy; signalling peptide.