A unifying conceptual model for the environmental responses of isoprene emissions from plants
Author(s)
Type
Journal Article
Abstract
Background and Aims
Isoprene is the most important volatile organic compound emitted by land plants in terms of
abundance and environmental effects. Controls on isoprene emission rates include light, temperature, water supply
and CO
2
concentration. A need to quantify these controls has long been recognized. There are already models that
give realistic results, but they are complex, highly empirical and require separate responses to different drivers.
This study sets out to find a simpler, unifying principle.
†
Methods
A simple model is presented based on the idea of balancing demands for reducing power (derived from
photosynthetic electron transport) in primary metabolism versus the secondary pathway that leads to the synthesis
of isoprene. This model’s ability to account for key features in a variety of experimental data sets is assessed.
†
Key results
The model simultaneously predicts the fundamental responses observed in short-term experiments,
namely: (1) the decoupling between carbon assimilation and isoprene emission; (2) a continued increase in isoprene
emission with photosynthetically active radiation (PAR) at high PAR, after carbon assimilation has saturated; (3) a
maximum of isoprene emission at low internal CO
2
concentration (
c
i
) and an asymptotic decline thereafter with in-
creasing
c
i
; (4) maintenance of high isoprene emissions when carbon assimilation is restricted by drought; and (5) a
temperature optimum higher than that of photosynthesis, but lower than that of isoprene synthase activity.
†
Conclusions
A simple model was used to test the hypothesisthat reducing poweravailable to the synthesis pathway
for isoprene varies according to the extent to which the needs of carbon assimilation are satisfied. Despite its simpli-
city the model explains much in terms of the observed response of isoprene to external drivers as well asthe observed
decoupling between carbon assimilation and isoprene emission. The concept has the potential to improve global-
scale modelling of vegetation isoprene emission.
Isoprene is the most important volatile organic compound emitted by land plants in terms of
abundance and environmental effects. Controls on isoprene emission rates include light, temperature, water supply
and CO
2
concentration. A need to quantify these controls has long been recognized. There are already models that
give realistic results, but they are complex, highly empirical and require separate responses to different drivers.
This study sets out to find a simpler, unifying principle.
†
Methods
A simple model is presented based on the idea of balancing demands for reducing power (derived from
photosynthetic electron transport) in primary metabolism versus the secondary pathway that leads to the synthesis
of isoprene. This model’s ability to account for key features in a variety of experimental data sets is assessed.
†
Key results
The model simultaneously predicts the fundamental responses observed in short-term experiments,
namely: (1) the decoupling between carbon assimilation and isoprene emission; (2) a continued increase in isoprene
emission with photosynthetically active radiation (PAR) at high PAR, after carbon assimilation has saturated; (3) a
maximum of isoprene emission at low internal CO
2
concentration (
c
i
) and an asymptotic decline thereafter with in-
creasing
c
i
; (4) maintenance of high isoprene emissions when carbon assimilation is restricted by drought; and (5) a
temperature optimum higher than that of photosynthesis, but lower than that of isoprene synthase activity.
†
Conclusions
A simple model was used to test the hypothesisthat reducing poweravailable to the synthesis pathway
for isoprene varies according to the extent to which the needs of carbon assimilation are satisfied. Despite its simpli-
city the model explains much in terms of the observed response of isoprene to external drivers as well asthe observed
decoupling between carbon assimilation and isoprene emission. The concept has the potential to improve global-
scale modelling of vegetation isoprene emission.
Date Issued
2013-09-19
Date Acceptance
2013-07-09
Citation
ANNALS OF BOTANY, 2013, 112 (7), pp.1223-1238
ISSN
0305-7364
Publisher
Oxford University Press
Start Page
1223
End Page
1238
Journal / Book Title
ANNALS OF BOTANY
Volume
112
Issue
7
Copyright Statement
© The Author 2013. Published by Oxford University Press on behalf of the Annals of Botany Company. This is an Open Access article distributed
under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse,
distribution, and reproduction in any medium, provided the original work is properly cited.
under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse,
distribution, and reproduction in any medium, provided the original work is properly cited.
Identifier
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Subjects
Science & Technology
Life Sciences & Biomedicine
Plant Sciences
Isoprene
modelling
electron transport
photosynthesis
temperature
carbon dioxide
isoprene emission
volatile organic compounds
ATMOSPHERIC CO2 CONCENTRATION
VOLATILE ORGANIC-COMPOUNDS
SYNTHASE ACTIVITY
MONOTERPENE EMISSION
QUERCUS-ROBUR
TEMPERATURE-ACCLIMATION
TROPOSPHERIC CHEMISTRY
BIOCHEMICAL-MODEL
NITRATE REDUCTASE
BIOGENIC ISOPRENE
Butadienes
Carbon Dioxide
Electrons
Environment
Hemiterpenes
Light
Models, Biological
NADP
Pentanes
Photosynthesis
Plants
Temperature
0607 Plant Biology
0602 Ecology
Plant Biology & Botany
Publication Status
Published