QTL mapping of flowering and fruiting traits in olive

Ines Ben Sadok (1, 2, 3) , Jean-Marc Celton (4) , Laila Essalouh (1, 4) , Amal Zine El Aabidine (5, 1) , Gilbert Garcia (1) , Sébastien Martinez (1) , Naziha Grati-Kamoun (2) , Ahmed-Riadh Rebai (3) , Evelyne Costes (1, 6) , Bouchaib Khadari (1)

1 UMR AGAP - Amélioration génétique et adaptation des plantes méditerranéennes et tropicales
2 Institut de l’olivier de Sfax
3 Université de Sfax - University of Sfax
4 IRHS - Institut de Recherche en Horticulture et Semences
5 UMR Ameliorat Genet & Adaptat Plantes Mediterrane
6 AFEF - Architecture et Fonctionnement des Espèces Fruitières [AGAP]

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 'Oliviere' 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 specific 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.

Mots clés: TREE ARCHITECTURE; BUD GROWTH; APPLE; MARKERS; CULTIVARS; DIFFERENTIATION; LINKAGE MAPS; BIENNIAL BEARING; OLEA-EUROPAEA; BRANCHING PATTERNS

Domaines: Sciences du Vivant [q-bio]

Ines Ben Sadok, Jean-Marc Celton, Laila Essalouh, Amal Zine El Aabidine, Gilbert Garcia, et al.. QTL mapping of flowering and fruiting traits in olive. PLoS ONE, 2013, 8 (5), ⟨10.1371/journal.pone.0062831⟩. ⟨hal-01209909⟩