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Genetic variability of carbon isotope discrimination in seedlings from Populus nigra L. populations grown under contrasting temperatures

Abstract : Climatic events predicted for this century should involve drier and warmer summers, such as those that occurred in 2003 and 2005 in France. The higher temperatures could become a limiting factor for the regeneration of Populus nigra L. species. During establishment and development in summer period, seedlings must be able to resist high temperatures (until 57.8°C on sand on a Loire island in July 2009). Therefore, maintaining a high transpiration rate (E) for leaf cooling (and therefore a high stomatal conductance to water vapour (gs)), may be a prerequisite for seedlings to survive under high temperatures. To test this hypothesis, we used bulk leaf carbon isotope discrimination (Δ) as a time-integrated index of gas exchange activity (Farquhar et al. 1989). The objectives of this study were (1) to explore the genetic variability of ∆ among P. nigra seedlings from different female trees coming from contrasting sites and (2) the plasticity in response to two contrasting temperatures. Seeds from 16 open-pollinated females originating from the Loire river (France) and from the Paglia river (Italy) were first grown during 7 weeks in two growth chambers at 25°C. At this time (t0), one chamber remained at 25°C and in the second one, the temperature progressively increased until 43°C until the first symptoms of wilting appeared (t1). At t0, an important genetic variability for ∆ (∆t0 25°C) was measured ranged from 24.0‰ to 28.0‰ in both chambers, but no provenances differences were detected. At t1, an important genetic variability for ∆t1 25°C and ∆t1 43°C was observed ranged from 22.0‰ to 26.0‰ in each chamber and a significant provenance effect was detected. At t1, ∆t1 43°C values were significantly higher (0.5‰) than ∆t1 25°C. Moreover, a significant correlation was detected between the ∆t1 43°C values and the symptoms of wilting seedlings, seedlings totally healthy exhibiting higher ∆t1 43°C values. We conclude, under the hypothesis that ∆ is mainly controlled by gs, as already reported in poplar species (Monclus et al. 2006), maintaining high E and therefore high ∆ may enable seedlings to survive under high temperature.
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Submitted on : Wednesday, June 3, 2020 - 8:15:24 PM
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  • HAL Id : hal-02754086, version 1
  • PRODINRA : 39732

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Sylvain Chamaillard, Marc Villar, Régis Fichot, Maurizio Sabatti, Fiorella Villani, et al.. Genetic variability of carbon isotope discrimination in seedlings from Populus nigra L. populations grown under contrasting temperatures. 5. International Poplar Symposium;IPS V, Sep 2010, Orvieto, Italy. ⟨hal-02754086⟩

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