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Title: Monoterpene ‘thermometer’ of tropical forest-atmosphere response to climate warming

Tropical forests absorb large amounts of atmospheric CO 2 through photosynthesis but elevated temperatures suppress this absorption and promote monoterpene emissions. Using 13CO 2 labeling, in this paper we show that monoterpene emissions from tropical leaves derive from recent photosynthesis and demonstrate distinct temperature optima for five groups (Groups 1–5), potentially corresponding to different enzymatic temperature-dependent reaction mechanisms within β-ocimene synthases. As diurnal and seasonal leaf temperatures increased during the Amazonian 2015 El Niño event, leaf and landscape monoterpene emissions showed strong linear enrichments of β-ocimenes (+4.4% °C -1) at the expense of other monoterpene isomers. The observed inverse temperature response of α-pinene (-0.8% °C -1), typically assumed to be the dominant monoterpene with moderate reactivity, was not accurately simulated by current global emission models. Given that β-ocimenes are highly reactive with respect to both atmospheric and biological oxidants, the results suggest that highly reactive β-ocimenes may play important roles in the thermotolerance of photosynthesis by functioning as effective antioxidants within plants and as efficient atmospheric precursors of secondary organic aerosols. Monoterpene composition may represent a new sensitive ‘thermometer’ of leaf oxidative stress and atmospheric reactivity, and therefore a new tool in future studies of warming impacts on tropical biosphere-atmospheremore » carbon-cycle feedbacks.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4] ;  [5] ;  [2] ;  [2] ;  [6]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Climate and Ecosystem Sciences Division
  2. National Inst. for Amazon Research (INPA), Manaus (Brazil)
  3. National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Lab.
  4. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Climate and Ecosystem Sciences Division. Joint BioEnergy Inst.
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Climate and Ecosystem Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Geography
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Plant, Cell and Environment
Additional Journal Information:
Journal Volume: 40; Journal Issue: 3; Journal ID: ISSN 0140-7791
Publisher:
Wiley
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); National Inst. for Amazon Research (INPA), Manaus (Brazil)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Council for Scientific and Technological Development (CNPq) (Brazil)
Country of Publication:
United States
Language:
English
Subject:
13Co2 labeling; drought; El Niño; heat; photosynthesis; carbon reactions; secondary organic aerosols; TPS synthase; volatile emissions
OSTI Identifier:
1435079