title: Beyond the meristems: similarities in the CLAVATA3 and INFLORESCENCE DEFICIENT IN ABSCISSION peptide mediated signalling pathways.
abstract: Plants form new organs throughout their lives; this requires a balance between cell proliferation and differentiation, and between the generation and loss of organs. To do this, plants must maintain a population of stem cells within the meristems, and at the same time, closely control the identity and position of cells at the meristem boundaries as they differentiate to new leaf or flower primordia. Once developed, organs may need to be shed, either as a controlled developmental decision-such as floral abscission after pollination, or as a response to disease, environmental stress, and predators. Cell wall degradation at specialized abscission zone (AZ) cells needs to occur for this to take place, but since there is little cell rearrangement in plants, cell separation events are also important for plant architecture. In this Opinion paper we discuss the role of two peptide ligand signalling systems that control stem cell homeostasis and cell separation, respectively. We draw parallels between the signalling pathways and explore on the commonalities of the downstream components activated and controlled by the signalling peptides. We provide evidence for AZ cells having a meristem identity and discuss the role of identical KNOTTED-LIKE HOMEOBOX (KNOX) transcription factors in meristem maintenance and abscission. Lastly we explore the evolutionary relationship between the pathways.
authors.affiliation: Department of Biosciences, Section for Genetics and Evolutionary Biology, University of Oslo, 0316 Oslo, Norway m.a.butenko@ibv.uio.no ruediger.simon@hhu.de.
authors.forename: Melinka A
authors.initials: MA
authors.lastname: Butenko
authors.affiliation: Institute for Developmental Genetics and Cluster of Excellence on Plant Sciences (CEPLAS), Universitätsstr. 1, Heinrich-Heine University, 40225 Düsseldorf, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Simon
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018519:Meristem / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; C512213:IDA protein, Arabidopsis
keywords: Abscission; CLAVATA; INFLORESCENCE DEFICIENT IN ABSCISSION; cell differentiation; cell proliferation; receptor-kinase; signalling; stem cells.