Login / Signup

Hot drought reduces the effects of elevated CO2 on tree water-use efficiency and carbon metabolism.

Benjamin BiramiThomas NaegeleMarielle GattmannYakir PreislerAndreas GastAlmut ArnethNadine Katrin Ruehr
Published in: The New phytologist (2020)
Trees are increasingly exposed to hot droughts due to CO2 -induced climate change. However, the direct role of [CO2 ] in altering tree physiological responses to drought and heat stress remains ambiguous. Pinus halepensis (Aleppo pine) trees were grown from seed under ambient (421 ppm) or elevated (867 ppm) [CO2 ]. The 1.5-yr-old trees, either well watered or drought treated for 1 month, were transferred to separate gas-exchange chambers and the temperature gradually increased from 25°C to 40°C over a 10 d period. Continuous whole-tree shoot and root gas-exchange measurements were supplemented by primary metabolite analysis. Elevated [CO2 ] reduced tree water loss, reflected in lower stomatal conductance, resulting in a higher water-use efficiency throughout amplifying heat stress. Net carbon uptake declined strongly, driven by increases in respiration peaking earlier in the well-watered (31-32°C) than drought (33-34°C) treatments unaffected by growth [CO2 ]. Further, drought altered the primary metabolome, whereas the metabolic response to [CO2 ] was subtle and mainly reflected in enhanced root protein stability. The impact of elevated [CO2 ] on tree stress responses was modest and largely vanished with progressing heat and drought. We therefore conclude that increases in atmospheric [CO2 ] cannot counterbalance the impacts of hot drought extremes in Aleppo pine.
Keyphrases
  • heat stress
  • climate change
  • heat shock
  • plant growth
  • arabidopsis thaliana
  • particulate matter
  • oxidative stress
  • room temperature
  • high glucose
  • endothelial cells
  • carbon dioxide
  • human health
  • amino acid
  • drug induced