title: Adventitious rooting declines with the vegetative to reproductive switch and involves a changed auxin homeostasis.
abstract: Adventitious rooting, whereby roots form from non-root tissues, is critical to the forestry and horticultural industries that depend on propagating plants from cuttings. A major problem is that age of the tissue affects the ability of the cutting to form adventitious roots. Here, a model system has been developed using Pisum sativum to differentiate between different interpretations of ageing. It is shown that the decline in adventitious rooting is linked to the ontogenetic switch from vegetative to floral and is mainly attributed to the cutting base. Using rms mutants it is demonstrated that the decline is not a result of increased strigolactones inhibiting adventitious root formation. Monitoring endogenous levels of a range of other hormones including a range of cytokinins in the rooting zone revealed that a peak in jasmonic acid is delayed in cuttings from floral plants. Additionally, there is an early peak in indole-3-acetic acid levels 6h post excision in cuttings from vegetative plants, which is absent in cuttings from floral plants. These results were confirmed using DR5:GUS expression. Exogenous supplementation of young cuttings with either jasmonic acid or indole-3-acetic acid promoted adventitious rooting, but neither of these hormones was able to promote adventitious rooting in mature cuttings. DR5:GUS expression was observed to increase in juvenile cuttings with increasing auxin treatment but not in the mature cuttings. Therefore, it seems the vegetative to floral ontogenetic switch involves an alteration in the tissue's auxin homeostasis that significantly reduces the indole-3-acetic acid pool and ultimately results in a decline in adventitious root formation.
authors.affiliation: Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent 9000, Belgium Plant and Crop Sciences, The University of Nottingham, Sutton Bonington LE12 5RD, UK razda5@gmail.com.
authors.forename: Amanda
authors.initials: A
authors.lastname: Rasmussen
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, Correnstrasse 3, 06466 Gatersleben, Germany.
authors.forename: Seyed Abdollah
authors.initials: SA
authors.lastname: Hosseini
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, Correnstrasse 3, 06466 Gatersleben, Germany.
authors.forename: Mohammed-Reza
authors.initials: MR
authors.lastname: Hajirezaei
authors.affiliation: Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Kuehnhaeuser Strasse 101, 99090 Erfurt, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Druege
authors.affiliation: Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent 9000, Belgium.
authors.forename: Danny
authors.initials: D
authors.lastname: Geelen
mesh_terms: D003517:Cyclopentanes / Q000378:metabolism; D006706:Homeostasis; D007210:Indoleacetic Acids / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism; D018532:Pisum sativum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; D007210:Indoleacetic Acids; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; C011006:jasmonic acid; C030737:indoleacetic acid
keywords: Adventitious roots; auxin; cytokinin; flowering induction; jasmonic acid; maturation; strigolactone.