QTL mapping of flowering and fruiting traits in olive

PLoS One. 2013 May 17;8(5):e62831. doi: 10.1371/journal.pone.0062831. Print 2013.

Abstract

One of the challenge fruit growers are facing is to balance between tree production and vegetative growth from year to year. To investigate the existence of genetic determinism for reproductive behaviour in olive tree, we studied an olive segregating population derived from a cross between 'Olivière' and 'Arbequina' cultivars. Our strategy was based on (i) an annual assessment of individual trees yield, and (ii) a decomposition of adult growth units at the crown periphery into quantitative variables related to both flowering and fruiting process in relation to their growth and branching. Genetic models, including the year, genotype effects and their interactions, were built with variance function and correlation structure of residuals when necessary. Among the progeny, trees were either 'ON' or 'OFF' for a given year and patterns of regular vs. irregular bearing were revealed. Genotype effect was significant on yield but not for flowering traits at growth unit (GU) scale, whereas the interaction between genotype and year was significant for both traits. A strong genetic effect was found for all fruiting traits without interaction with the year. Based on the new constructed genetic map, QTLs with small effects were detected, revealing multigenic control of the studied traits. Many were associated to alleles from 'Arbequina'. Genetic correlations were found between Yield and Fruit set at GU scale suggesting a common genetic control, even though QTL co-localisations were in spe`cific years only. Most QTL were associated to flowering traits in specific years, even though reproductive traits at GU scale did not capture the bearing status of the trees in a given year. Results were also interpreted with respect to ontogenetic changes of growth and branching, and an alternative sampling strategy was proposed for capturing tree fruiting behaviour. Regular bearing progenies were identified and could constitute innovative material for selection programs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Mapping
  • Crosses, Genetic
  • Flowers / genetics*
  • Fruit / genetics*
  • Genotype
  • Models, Genetic
  • Olea / genetics*
  • Olea / growth & development
  • Quantitative Trait Loci / genetics*

Grants and funding

This work was financed by the Department of Genetics and Plant Breeding of INRA (Institut National de la Recherche Agronomique) Montpellier and FranceAgriMer SIVAL n° 2010-1919 project “RegulOlive”. Inès Ben Sadok was supported by fellowships from Erasmus-Averroes and French University Agency. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.