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Tree Physiol

Title:		Leaf-level metabolic changes in response to drought affect daytime CO2 emission and isoprenoid synthesis pathways
Author(s):		Ladd SN; Daber LE; Bamberger I; Kubert A; Kreuzwieser J; Purser G; Ingrisch J; Deleeuw J; Haren J; Meredith LK; Werner C;
Address:		"Ecosystem Physiology, University of Freiburg, Georges-Kohler-Allee 053/054, 79110 Freiburg, Germany. Department of Environmental Sciences, University of Basel, Bernoullistrasse 30, 4056 Basel, Switzerland. School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK. UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, EH26 0QB, U K. Department of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria. Biosphere 2, University of Arizona, 32540 S. Biosphere Rd., Oracle, AZ, 85739, USA. Honors College, University of Arizona, 1101 E. Mabel Street, Tucson, AZ, 85719, USA. School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, USA"
Journal Title:		Tree Physiol
Year:		2023
Volume:		20230808
Issue:
Page Number:		-
DOI:		10.1093/treephys/tpad094
ISSN/ISBN:		1758-4469 (Electronic) 0829-318X (Linking)
Abstract:		"In the near future, climate change will cause enhanced frequency and/or severity of droughts in terrestrial ecosystems, including tropical forests. Drought responses by tropical trees may affect their carbon use, including production of volatile organic compounds (VOCs), with implications for carbon cycling and atmospheric chemistry that are challenging to predict. It remains unclear how metabolic adjustments by mature tropical trees in response to drought will affect their carbon fluxes associated with daytime CO2 production and VOC emission. To address this gap, we used position-specific 13C-pyruvate labeling to investigate leaf CO2 and VOC fluxes from four tropical species before and during a controlled drought in the enclosed rainforest of Biosphere 2. Overall, plants that were more drought-sensitive to drought had greater reductions in daytime CO2 production. Although daytime CO2 production was always dominated by non-mitochondrial processes, the relative contribution of CO2 from the tricarboxylic acid cycle tended to increase under drought. A notable exception was the legume tree Clitoria fairchildiana, which had less anabolic CO2 production than the other species even under pre-drought conditions, perhaps due to more efficient refixation of CO2 and anaplerotic use for amino acid synthesis. C. fairchildiana was also the only species to allocate detectable amounts of 13C label to VOCs, and was a major source of VOCs in Biosphere 2. In C. fairchildiana leaves, our data indicate that intermediates from the mevalonic acid pathway are used to produce the volatile monoterpene trans-beta-ocimene, but not isoprene. This apparent crosstalk between the mevalonic acid and methylerythritol phosphate pathways for monoterpene synthesis declined with drought. Finally, although trans-beta-ocimene emissions increased under drought, it was increasingly sourced from stored intermediates and not de novo synthesis. Unique metabolic responses of legumes may play a disproportionate role in the overall changes in daytime CO2 and VOC fluxes in tropical forests experiencing drought"
Keywords:		Gc-irms PTR-ToF-MS daytime respiration drought isoprenoids legumes position-specific isotope labeling tropical plants volatile organic compounds;
Notes:		"PublisherLadd, S Nemiah Daber, L Erik Bamberger, Ines Kubert, Angelika Kreuzwieser, Jurgen Purser, Gemma Ingrisch, Johannes Deleeuw, Jason Haren, Joost Meredith, Laura K Werner, Christiane eng Canada 2023/08/08 Tree Physiol. 2023 Aug 8:tpad094. doi: 10.1093/treephys/tpad094"