title: Floral organ abscission peptide IDA and its HAE/HSL2 receptors control cell separation during lateral root emergence.
abstract: Throughout their life cycle, plants produce new organs, such as leaves, flowers, and lateral roots. Organs that have served their purpose may be shed after breakdown of primary cell walls between adjacent cell files at the site of detachment. In Arabidopsis, floral organs abscise after pollination, and this cell separation event is controlled by the peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA), which signals through the leucine-rich repeat receptor-like kinases HAESA (HAE) and HAESA-LIKE2 (HSL2). Emergence of new lateral root primordia, initiated deep inside the root under the influence of auxin, is similarly dependent on cell wall dissolution between cells in the overlaying endodermal, cortical, and epidermal tissues. Here we show that this process requires IDA, HAE, and HSL2. Mutation in these genes constrains the passage of the growing lateral root primordia through the overlaying layers, resulting in altered shapes of the lateral root primordia and of the overlaying cells. The HAE and HSL2 receptors are redundant in function during floral organ abscission, but during lateral root emergence they are differentially involved in regulating cell wall remodeling genes. In the root, IDA is strongly auxin-inducible and dependent on key regulators of lateral root emergence--the auxin influx carrier LIKE AUX1-3 and AUXIN RESPONSE FACTOR7. The expression levels of the receptor genes are only transiently induced by auxin, suggesting they are limiting factors for cell separation. We conclude that elements of the same cell separation signaling module have been adapted to function in different developmental programs.
authors.affiliation: Department of Biosciences, University of Oslo, Blindern, 0316 Oslo, Norway.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Kumpf
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Shi
authors.forename: Antoine
authors.initials: A
authors.lastname: Larrieu
authors.forename: Ida Myhrer
authors.initials: IM
authors.lastname: Stø
authors.forename: Melinka A
authors.initials: MA
authors.lastname: Butenko
authors.forename: Benjamin
authors.initials: B
authors.lastname: Péret
authors.forename: Even Sannes
authors.initials: ES
authors.lastname: Riiser
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Bennett
authors.forename: Reidunn B
authors.initials: RB
authors.lastname: Aalen
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D009154:Mutation; D063245:Plant Development / Q000502:physiology*; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C503425:ARF7 protein, Arabidopsis; C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C512213:IDA protein, Arabidopsis; D014157:Transcription Factors; C089427:RLK5 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases