NEVERSHED and INFLORESCENCE DEFICIENT IN ABSCISSION are differentially required for cell expansion and cell separation during floral organ abscission in Arabidopsis thaliana

• Published in: Journal of experimental botany Vol. 64; no. 17; pp. 5345 - 5357
• Main Authors: Liu, Bin, Butenko, Melinka A, Shi, Chun-Lin, Bolivar, Jenny L, Winge, Per, Stenvik, Grethe-Elisabeth, Vie, Ane Kjersti, Leslie, Michelle E, Brembu, Tore, Kristiansen, Wenche, Bones, Atle M, Patterson, Sara E, Liljegren, Sarah J, Aalen, Reidunn B
• Format: Journal Article
• Language: English
• Published: England Oxford University Press [etc.] 01-12-2013; Oxford University Press
• Subjects: Abscission; Arabidopsis - anatomy & histology; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Cell Proliferation; Cell separation; Cell Wall - metabolism; Cell walls; Down-Regulation; flowers; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant; Genes; GTPase-activating proteins; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; Inflorescence - anatomy & histology; Inflorescence - genetics; Inflorescence - physiology; Inflorescences; Iron deficiency anemia; kinases; Models, Biological; multigene family; mutants; Mutation; Oligonucleotide Array Sequence Analysis; Peptides - genetics; Peptides - metabolism; Petals; Phenotype; Phenotypes; physiological transport; Plants; Plants, Genetically Modified; Protein Transport; RESEARCH PAPER; Signal Transduction; transcription (genetics); scanning electron microscopy; cell-to-cell communication; signalling peptide; petal breakstrength; cell wall loosening; ARF-GAP; cell wall degradation
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ert232

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.