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Front. Plant Sci. | doi: 10.3389/fpls.2019.01233

Impact of within-tree organ distances on floral induction and fruit growth in apple tree: implication of carbohydrate and gibberellin organ contents

 Farés Belhassine1, Sébastien Martinez1, Sylvie Bluy1, Damien Fumey2, Jean-Jacques Kelner3,  Evelyne Costes1 and  Benoît Pallas1*
  • 1Institut National de la Recherche Agronomique Centre Montpellier, France
  • 2ITK, France
  • 3Montpellier SupAgro, France

In plants, organs are inter-dependent for growth and development. Here, we aimed to investigate the distance at which interaction between organs operates and the relative contribution of within-tree variation in carbohydrate and hormonal contents on floral induction and fruit growth, in a fruit tree case study. Manipulations of leaf and fruit numbers were performed in two years on ‘Golden delicious’ apple trees, at the shoot or branch scale or one side of Y-shape trees. For each treatment, floral induction proportion and mean fruit weight were recorded. Gibberellins content in shoot apical meristems, photosynthesis, and non-structural carbohydrate concentrations in organs were measured. Floral induction was promoted by leaf presence and fruit absence but was not associated with non-structural content in meristems. This suggests a combined action of promoting and inhibiting signals originating from leaves and fruit, and involving gibberellins. Nevertheless, these signals act at short distance only since leaf or fruit presence at long distances had no effect on floral induction. Conversely, fruit growth was affected by leaf presence even at long distances when sink demands were imbalanced within the tree, suggesting long distance transport of carbohydrates. We thus clarified the inter-dependence and distance effect among organs, therefore their degree of autonomy that appeared dependent on the process considered, floral induction or fruit growth.

Keywords: leaf/fruit removal, floral induction, Fruit weight, Non-structural carbohydrates (NSC), source-sink relationships., shoot/branch autonomy, Malus × domestica Borkh

Received: 02 May 2019; Accepted: 05 Sep 2019.

Copyright: © 2019 Belhassine, Martinez, Bluy, Fumey, Kelner, Costes and Pallas. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Benoît Pallas, Institut National de la Recherche Agronomique Centre Montpellier, Montpellier, 34000, Languedoc-Roussillon, France, pallas@supagro.inra.fr