Temperature affects somatic embryo development in maritime pine.
In: Bonga J.M., Park Y.-S., Trontin J.-F. (Eds), 2019. Proceedings of the 5th International Conference of the IUFRO Working Party 2.09.02 on “Clonal Trees in The Bioeconomy Age: Opportunities and Challenges”, Coimbra, Portugal, Sept. 10-15, 2018, pp. 274.
Trontin, JF, Reymond I, Canlet F, Sow MD, Delaunay A, Maury S, Le Metté C, Teyssier C, Lelu-Walter MA
Collaboration FCBA, INRAE (BioFoRA), Univ. Orléans (LBLGC)
XYLOBIOTECH technical support:
In vitro culture
The adaptability of forest tree varieties to the environmental stresses induced by global warming is still largely unknown. This is a major concern for foresters because climate change could affect a crucial reproductive function of trees: seed production. In some conifers such as Norway spruce, temperature during embryogenesis has been shown to affect the development of both somatic and zygotic embryos as well as, a posteriori, plant phenology over several years of juvenile vegetative phase. Temperature effects on embryo development are particularly difficult to investigate in situ, e.g. in seed orchards. As a good in vitro model system of embryo development, we used the best somatic embryogenesis protocols currently available for maritime pine at FCBA and INRA (Trontin et al. 2016) to study the temperature effect (18, 23 and 28°C) when applied during the maturation phase of cotyledonary embryos. We showed for two unrelated maritime pine embryogenic lines (PN519 and AAY06006) that the temperature during embryogenesis has major impacts on the development of cotyledonary embryos (duration, yield, mass) and that these direct effects are complemented with delayed effects (estimated in up to 15-month-old emblings) on germination capacity, survival, initial growth in height and the phenology of plant development. Genotypic effects possibly related to the line’s pedigree were also highlighted. Indirectly our results suggest that temperature affects the intrinsic quality of cotyledonary embryos which could be reduced at maturation temperatures lower (18°C) or higher (28°C) than the reference temperature (23°C). No significant differences in global DNA methylation could be detected among the tested maturation conditions in both immature (1 week maturation) and cotyledonary embryos (10-14 weeks maturation) from line PN519. Further biochemical, proteomic and methylome analyses are ongoing to clarify the physiological and molecular mechanisms involved in embryos' perception of temperature in maritime pine.