Plasticity of primary and secondary growth dynamics in Eucalyptus hybrids: A quantitative genetics and QTL mapping perspective

Bartholomé Jérôme, Salmon Frédéric, Vigneron Philippe, Bouvet Jean-Marc, Plomion Christophe, Gion Jean-Marc. 2013. Plasticity of primary and secondary growth dynamics in Eucalyptus hybrids: A quantitative genetics and QTL mapping perspective. BMC Plant Biology, 13 (120), 14 p.

https://doi.org/10.1186/1471-2229-13-120

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Quartile : Q1, Sujet : PLANT SCIENCES

Résumé : Background: The genetic basis of growth traits has been widely studied in forest trees. Quantitative trait locus (QTL) studies have highlighted the presence of both stable and unstable genomic regions accounting for biomass production with respect to tree age and genetic background, but results remain scarce regarding the interplay between QTLs and the environment. In this study, our main objective was to dissect the genetic architecture of the growth trajectory with emphasis on genotype x environment interaction by measuring primary and secondary growth covering intervals connected with environmental variations. Results: Three different trials with the same family of Eucalyptus urophylla x E. grandis hybrids (with different genotypes) were planted in the Republic of Congo, corresponding to two QTL mapping experiments and one clonal test. Height and radial growths were monitored at regular intervals from the seedling stage to five years old. The correlation between growth increments and an aridity index revealed that growth before two years old (r = 0.5; 0.69) was more responsive to changes in water availability than late growth (r = 0.39; 0.42) for both height and circumference. We found a regular increase in heritability with time for cumulative growth for both height [0.06 - 0.33] and circumference [0.06 - 0.38]. Heritabilities for incremental growth were more heterogeneous over time even if ranges of variation were similar (height [0-0.31]; circumference [0.19 to 0.48]). Within the trials, QTL analysis revealed collocations between primary and secondary growth QTLs as well as between early growth increments and final growth QTLs. Between trials, few common QTLs were detected highlighting a strong environmental effect on the genetic architecture of growth, validated by significant QTL x E interactions. Conclusion: These results suggest that early growth responses to water availability determine the genetic architecture of total growth at the mature stage and highlight the importance of considering growth as a composite trait (such as yields for annual plants) for a better understanding of its genetic bases.

Mots-clés Agrovoc : Eucalyptus grandis, Eucalyptus urophylla, hybride, héritabilité, croissance, locus des caractères quantitatifs, modèle de croissance forestière, plasticité, paramètre génétique, sélection

Mots-clés géographiques Agrovoc : République démocratique du Congo

Classification Agris : K10 - Production forestière
F62 - Physiologie végétale - Croissance et développement
F30 - Génétique et amélioration des plantes

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

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