title: On the role of ethylene, auxin and a GOLVEN-like peptide hormone in the regulation of peach ripening.
abstract: BACKGROUND
  In melting flesh peaches, auxin is necessary for system-2 ethylene synthesis and a cross-talk between ethylene and auxin occurs during the ripening process. To elucidate this interaction at the transition from maturation to ripening and the accompanying switch from system-1 to system-2 ethylene biosynthesis, fruits of melting flesh and stony hard genotypes, the latter unable to produce system-2 ethylene because of insufficient amount of auxin at ripening, were treated with auxin, ethylene and with 1-methylcyclopropene (1-MCP), known to block ethylene receptors. The effects of the treatments on the different genotypes were monitored by hormone quantifications and transcription profiling.
  
  
  RESULTS
  In melting flesh fruit, 1-MCP responses differed according to the ripening stage. Unexpectedly, 1-MCP induced genes also up-regulated by ripening, ethylene and auxin, as CTG134, similar to GOLVEN (GLV) peptides, and repressed genes also down-regulated by ripening, ethylene and auxin, as CTG85, a calcineurin B-like protein. The nature and transcriptional response of CTG134 led to discover a rise in free auxin in 1-MCP treated fruit. This increase was supported by the induced transcription of CTG475, an IAA-amino acid hydrolase. A melting flesh and a stony hard genotype, differing for their ability to synthetize auxin and ethylene amounts at ripening, were used to study the fine temporal regulation and auxin responsiveness of genes involved in the process. Transcriptional waves showed a tight interdependence between auxin and ethylene actions with the former possibly enhanced by the GLV CTG134. The expression of genes involved in the regulation of ripening, among which are several transcription factors, was similar in the two genotypes or could be rescued by auxin application in the stony hard. Only GLV CTG134 expression could not be rescued by exogenous auxin.
  
  
  CONCLUSIONS
  1-MCP treatment of peach fruit is ineffective in delaying ripening because it stimulates an increase in free auxin. As a consequence, a burst in ethylene production speeding up ripening occurs. Based on a network of gene transcriptional regulations, a model in which appropriate level of CTG134 peptide hormone might be necessary to allow the correct balance between auxin and ethylene for peach ripening to occur is proposed.
authors: Dipartimento di Biologia, Università di Padova, Viale G. Colombo 3, I-35121, Padova, Italy. alice.tadiello@gmail.com.|Present addresses: Research and Innovation Centre, Fondazione Edmund Mach, Via Mach 1, 38010, San Michele all'Adige, Trento, Italy. alice.tadiello@gmail.com.
authors: Alice
authors: A
authors: Tadiello
authors: Dipartimento di Colture Arboree, Università di Bologna, Viale Fanin 46, 40127, Bologna, Italy. ziosi@biolchim.it.|Present addresses: BIOLCHIM S.p.A., Via San Carlo 2130, 40059, Medicina, BO, Italy. ziosi@biolchim.it.
authors: Vanina
authors: V
authors: Ziosi
authors: Dipartimento di Scienze agrarie ambientali - Produzione - Territorio - Agroenergia (Di.S.A.A), Università degli Studi di Milano, via Celoria 2, Milan, I-20133, Italy. simonegri80@gmail.com.
authors: Alfredo Simone
authors: AS
authors: Negri
authors: Dipartimento di Colture Arboree, Università di Bologna, Viale Fanin 46, 40127, Bologna, Italy. massimo.noferini@famosasrl.com.|Present addresses: FA.MO.S.A s.r.l., Via Selice 84/A, 40026, Imola, BO, Italy. massimo.noferini@famosasrl.com.
authors: Massimo
authors: M
authors: Noferini
authors: Dipartimento di Colture Arboree, Università di Bologna, Viale Fanin 46, 40127, Bologna, Italy. giovanni.fiori@unibo.it.
authors: Giovanni
authors: G
authors: Fiori
authors: Dipartimento di Biologia, Università di Padova, Viale G. Colombo 3, I-35121, Padova, Italy. nbusatto@hotmail.com.|Present addresses: Dipartimento di Colture Arboree, Università di Bologna, Viale Fanin 46, 40127, Bologna, Italy. nbusatto@hotmail.com.
authors: Nicola
authors: N
authors: Busatto
authors: Dipartimento di Scienze agrarie ambientali - Produzione - Territorio - Agroenergia (Di.S.A.A), Università degli Studi di Milano, via Celoria 2, Milan, I-20133, Italy. luca.espen@unimi.it.
authors: Luca
authors: L
authors: Espen
authors: Dipartimento di Colture Arboree, Università di Bologna, Viale Fanin 46, 40127, Bologna, Italy. guglielmo.costa@unibo.it.
authors: Guglielmo
authors: G
authors: Costa
authors: Dipartimento di Biologia, Università di Padova, Viale G. Colombo 3, I-35121, Padova, Italy. livio.trainotti@unipd.it.
authors: Livio
authors: L
authors: Trainotti
mesh_terms: D005030:Ethylenes / Q000096:biosynthesis; D005638:Fruit / Q000254:growth & development*; D007210:Indoleacetic Acids; D036361:Peptide Hormones / Q000502:physiology*; D010937:Plant Growth Regulators / Q000502:physiology*; D000068239:Prunus persica / Q000254:growth & development*
chemical_list: D005030:Ethylenes; D007210:Indoleacetic Acids; D036361:Peptide Hormones; D010937:Plant Growth Regulators; C036216:ethylene