title: Analysis of transcripts differentially expressed between fruited and deflowered 'Gala' adult trees: a contribution to biennial bearing understanding in apple.
abstract: BACKGROUND
  The transition from vegetative to floral state in shoot apical meristems (SAM) is a key event in plant development and is of crucial importance for reproductive success. In perennial plants, this event is recurrent during tree life and subject to both within-tree and between-years heterogeneity. In the present study, our goal was to identify candidate processes involved in the repression or induction of flowering in apical buds of adult apple trees.
  
  
  RESULTS
  Genes differentially expressed (GDE) were examined between trees artificially set in either 'ON' or 'OFF' situation, and in which floral induction (FI) was shown to be inhibited or induced in most buds, respectively, using qRT-PCR and microarray analysis. From the period of FI through to flower differentiation, GDE belonged to four main biological processes (i) response to stimuli, including response to oxidative stress; (ii) cellular processes, (iii) cell wall biogenesis, and (iv) metabolic processes including carbohydrate biosynthesis and lipid metabolic process. Several key regulator genes, especially TEMPRANILLO (TEM), FLORAL TRANSITION AT MERISTEM (FTM1) and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) were found differentially expressed. Moreover, homologs of SPL and Leucine-Rich Repeat proteins were present under QTL zones previously detected for biennial bearing.
  
  
  CONCLUSIONS
  This data set suggests that apical buds of 'ON' and 'OFF' trees were in different physiological states, resulting from different metabolic, hormonal and redox status which are likely to contribute to FI control in adult apple trees. Investigations on carbohydrate and hormonal fluxes from sources to SAM and on cell detoxification process are expected to further contribute to the identification of the underlying physiological mechanisms of FI in adult apple trees.
authors.affiliation: INRA, UMR AGAP, CIRAD-INRA-SupAgro, AFEF team (Architecture et Fonctionnement des Espèces Fruitières) TA 108/03, Avenue Agropolis, 34398, Montpellier, CEDEX 5, France. baptiste.guitton@gmail.com.|ICRISAT, Samanko station, BP320, Bamako, Mali. baptiste.guitton@gmail.com.|CIRAD, UMR AGAP, CIRAD-INRA-SupAgro, TA 108/03, Avenue Agropolis, 34398, Montpellier, CEDEX 5, France. baptiste.guitton@gmail.com.|The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand. baptiste.guitton@gmail.com.
authors.forename: B
authors.initials: B
authors.lastname: Guitton
authors.affiliation: SupAgro, UMR AGAP, CIRAD-INRA-SupAgro, AFEF team (Architecture et Fonctionnement des Espèces Fruitières) TA 108/03, Avenue Agropolis, 34398, Montpellier, CEDEX 5, France. jean-jacques.kelner@supagro.inra.fr.
authors.forename: J J
authors.initials: JJ
authors.lastname: Kelner
authors.affiliation: INRA, UMR1345 IRHS, Institut de Recherche en Horticulture et Semences, AgroCampus-Ouest-INRA- QUASAV, Bretagne-Loire University, 49071, Beaucouzé, France. jean-marc.celton@angers.inra.fr.
authors.forename: J M
authors.initials: JM
authors.lastname: Celton
authors.affiliation: CIRAD, UMR AGAP, CIRAD-INRA-SupAgro, TA 108/03, Avenue Agropolis, 34398, Montpellier, CEDEX 5, France. xavier.sabau@cirad.fr.
authors.forename: X
authors.initials: X
authors.lastname: Sabau
authors.affiliation: INRA, UMR1345 IRHS, Institut de Recherche en Horticulture et Semences, AgroCampus-Ouest-INRA- QUASAV, Bretagne-Loire University, 49071, Beaucouzé, France. jean-pierre.renou@angers.inra.fr.
authors.forename: J P
authors.initials: JP
authors.lastname: Renou
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand. david.chagne@plantandfood.co.nz.
authors.forename: D
authors.initials: D
authors.lastname: Chagné
authors.affiliation: INRA, UMR AGAP, CIRAD-INRA-SupAgro, AFEF team (Architecture et Fonctionnement des Espèces Fruitières) TA 108/03, Avenue Agropolis, 34398, Montpellier, CEDEX 5, France. costes@supagro.inra.fr.
authors.forename: E
authors.initials: E
authors.lastname: Costes
mesh_terms: D035264:Flowers / Q000235:genetics; D005638:Fruit / Q000235:genetics* / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D027845:Malus / Q000235:genetics* / Q000254:growth & development; D014197:Trees / Q000235:genetics