Short-term nitrogen dynamics are impacted by defoliation and drought in Fagus sylvatica L. branches - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles Tree Physiology Year : 2019

Short-term nitrogen dynamics are impacted by defoliation and drought in Fagus sylvatica L. branches

Pierre-Antoine Chuste
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Catherine Massonnet
Dominique Gerant
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  • PersonId : 1205676
Joseph Levillain
Christian Hossann
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  • PersonId : 1204216
Nicolas Angeli
Rémi Wortemann
  • Function : Author
Nathalie Bréda
Pascale Maillard
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Abstract

The predicted recurrence of adverse climatic events such as droughts, which disrupt nutrient accessibility for trees, could jeopardize the nitrogen (N) metabolism in forest trees. Internal tree N cycling capacities are crucial to ensuring tree survival but how the N metabolism of forest trees responds to intense, repeated environmental stress is not well known. For 2 years, we submitted 9-year-old beech (Fagus sylvatica L.) trees to either a moderate or a severe prolonged drought or a yearly removal of 75% of the foliage to induce internal N cycling changes. During the second year of stress, in spring and summer, we sprayed N-15-urea on the leaves (one branch per tree). Then, for 14 days, we traced the N-15 dynamics through the leaves, into foliar proteins and into the branch compartments (leaves and stems segments), as well as its long-distance transfer from the labeled branches to the tree apical twigs. Defoliation caused a short- and mid-term N increase in the leaves, which remained the main sink for N. Whatever the treatment and the date, most of the leaf N-15 stayed in the leaves and was invested in soluble proteins (60-68% of total leaf N). N-15 stayed more in the proximal part of the branch in response to drought compared with other treatments. The long-distance transport of N was maintained even under harsh drought, highlighting efficient internal N recycling in beech trees. Under extreme constraints creating an N and water imbalance, compensation mechanisms operated at the branch level in beech trees and allowed them (i) to maintain leaf N metabolism and protein synthesis and (ii) to ensure the seasonal short- and long-distance transfer of recycled leaf N even under drastic water shortage conditions.
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hal-02624191 , version 1 (26-05-2020)

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Pierre-Antoine Chuste, Catherine Massonnet, Dominique Gerant, Bernhard Zeller, Joseph Levillain, et al.. Short-term nitrogen dynamics are impacted by defoliation and drought in Fagus sylvatica L. branches. Tree Physiology, 2019, 39 (5), pp.792-804. ⟨10.1093/treephys/tpz002⟩. ⟨hal-02624191⟩
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