title: Grape berry ripening delay induced by a pre-véraison NAA treatment is paralleled by a shift in the expression pattern of auxin- and ethylene-related genes.
abstract: BACKGROUND
  Auxins act as repressors of ripening inception in grape (véraison), while ethylene and abscisic acid (ABA) play a positive role as inducers of the syndrome. Despite the increasing amount of information made available on this topic, the complex network of interactions among these hormones remains elusive. In order to shed light on these aspects, a holistic approach was adopted to evaluate, at the transcriptomic level, the crosstalk between hormones in grape berries, whose ripening progression was delayed by applying naphtalenacetic acid (NAA) one week before véraison.
  
  
  RESULTS
  The NAA treatment caused significant changes in the transcription rate of about 1,500 genes, indicating that auxin delayed grape berry ripening also at the transcriptional level, along with the recovery of a steady state of its intracellular concentration. Hormone indices analysis carried out with the HORMONOMETER tool suggests that biologically active concentrations of auxins were achieved throughout a homeostatic recovery. This occurred within 7 days after the treatment, during which the physiological response was mainly unspecific and due to a likely pharmacological effect of NAA. This hypothesis is strongly supported by the up-regulation of genes involved in auxin conjugation (GH3-like) and action (IAA4- and IAA31-like). A strong antagonistic effect between auxin and ethylene was also observed, along with a substantial 'synergism' between auxins and ABA, although to a lesser extent.
  
  
  CONCLUSIONS
  This study suggests that, in presence of altered levels of auxins, the crosstalk between hormones involves diverse mechanisms, acting at both the hormone response and biosynthesis levels, creating a complex response network.
authors.affiliation: Department of Agronomy, Food, Natural resources, Animals and Environment, DAFNAE, University of Padova, Agripolis - Viale dell'Università 16, 35020, Legnaro, Padova, Italy.
authors.forename: Fiorenza
authors.initials: F
authors.lastname: Ziliotto
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Corso
authors.forename: Fabio Massimo
authors.initials: FM
authors.lastname: Rizzini
authors.forename: Angela
authors.initials: A
authors.lastname: Rasori
authors.forename: Alessandro
authors.initials: A
authors.lastname: Botton
authors.forename: Claudio
authors.initials: C
authors.lastname: Bonghi
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism*; D005638:Fruit / Q000235:genetics / Q000502:physiology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D007210:Indoleacetic Acids / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D009280:Naphthaleneacetic Acids / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000502:physiology*; D027843:Vitis / Q000235:genetics* / Q000502:physiology
chemical_list: D005030:Ethylenes; D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D010937:Plant Growth Regulators; D000040:Abscisic Acid; C036216:ethylene