title: An INDEHISCENT-Controlled Auxin Response Specifies the Separation Layer in Early Arabidopsis Fruit.
abstract: Seed dispersal is an important moment in the life cycle of a plant species. In Arabidopsis thaliana, it is dependent on transcription factor INDEHISCENT (IND)-mediated specification of a separation layer in the dehiscence zone found in the margin between the valves (carpel walls) and the central replum of the developing fruit. It was proposed that IND specifies the separation layer by inducing a local auxin minimum at late stages of fruit development. Here we show that morphological differences between the ind mutant and wild-type fruit already arise at early stages of fruit development, coinciding with strong IND expression in the valve margin. We show that IND-reduced PIN-FORMED3 (PIN3) auxin efflux carrier abundance leads to an increased auxin response in the valve margin during early fruit development, and that the concomitant cell divisions that form the dehiscence zone are lacking in ind mutant fruit. Moreover, IND promoter-driven ectopic expression of the AGC kinases PINOID (PID) and WAG2 induced indehiscence by expelling auxin from the valve margin at stages 14-16 of fruit development through increased PIN3 abundance. Our results show that IND, besides its role at late stages of Arabidopsis fruit development, functions at early stages to facilitate the auxin-triggered cell divisions that form the dehiscence zone.
authors.affiliation: Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, the Netherlands.
authors.forename: Kasper
authors.initials: K
authors.lastname: van Gelderen
authors.affiliation: Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, the Netherlands.
authors.forename: Martin
authors.initials: M
authors.lastname: van Rongen
authors.affiliation: Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, the Netherlands.
authors.forename: An'an
authors.initials: A
authors.lastname: Liu
authors.affiliation: Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, the Netherlands.
authors.forename: Anne
authors.initials: A
authors.lastname: Otten
authors.affiliation: Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, the Netherlands. Electronic address: r.offringa@biology.leidenuniv.nl.
authors.forename: Remko
authors.initials: R
authors.lastname: Offringa
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D005638:Fruit / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D007210:Indoleacetic Acids; D017346:Protein Serine-Threonine Kinases; C484035:INDEHISCENT protein, Arabidopsis; C449300:PIN3 protein, Arabidopsis; C405165:PINOID protein, Arabidopsis; C542125:WAG2 protein, Arabidopsis
keywords: Arabidopsis; INDEHISCENT; PINOID; polar auxin transport; seed dispersal; separation layer