Next Article in Journal
The Impacts of Native Forests and Forest Plantations on Water Supply in Chile
Previous Article in Journal
Mapping Coarse Woody Debris with Random Forest Classification of Centimetric Aerial Imagery
Open AccessArticle

Reassimilation of Leaf Internal CO2 Contributes to Isoprene Emission in the Neotropical Species Inga edulis Mart.

1
National Institute for Amazonian Research (INPA), Avenida André Araújo, 2936, Manaus CEP 69011-970, Amazonas, Brazil
2
Climate and Ecosystem Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Rd, Building 84-155, Berkeley, CA 94720, USA
3
Faculty of Chemical Engineering, State University of Amazonas, Avenida Darcy Vargas, 1200, Manaus CEP 69050-020, Amazonas, Brazil
4
Meteorology Department, State University of Amazonas, Avenida Darcy Vargas, 1200, Manaus CEP 69050-020, Amazonas, Brazil
*
Author to whom correspondence should be addressed.
Forests 2019, 10(6), 472; https://doi.org/10.3390/f10060472
Received: 13 April 2019 / Revised: 15 May 2019 / Accepted: 22 May 2019 / Published: 30 May 2019
(This article belongs to the Section Forest Ecophysiology and Biology)
Isoprene (C5H8) is a hydrocarbon gas emitted by many tree species and has been shown to protect photosynthesis under abiotic stress. Under optimal conditions for photosynthesis, ~70%–90% of carbon used for isoprene biosynthesis is produced from recently assimilated atmospheric CO2. While the contribution of alternative carbon sources that increase with leaf temperature and other stresses have been demonstrated, uncertainties remain regarding the biochemical source(s) of isoprene carbon. In this study, we investigated leaf isoprene emissions (Is) from neotropical species Inga edulis Mart. as a function of light and temperature under ambient (450 µmol m−2 s−1) and CO2-free (0 µmol m−2 s−1) atmosphere. Is under CO2-free atmosphere showed light-dependent emission patterns similar to those observed under ambient CO2, but with lower light saturation point. Leaves treated with the photosynthesis inhibitor DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) failed to produce detectable Is in normal light under a CO2-free atmosphere. While strong temperature-dependent Is were observed under CO2-free atmosphere in the light, dark conditions failed to produce detectable Is even at the highest temperatures studied (40 °C). Treatment of leaves with 13C-labeled sodium bicarbonate under CO2-free atmosphere resulted in Is with over 50% containing at least one 13C atom. Is under CO2-free atmosphere and standard conditions of light and leaf temperature represented 19% ± 7% of emissions under ambient CO2. The results show that the reassimilation of leaf internal CO2 contributes to Is in the neotropical species I. edulis. Through the consumption of excess photosynthetic energy, our results support a role of isoprene biosynthesis, together with photorespiration, as a key tolerance mechanism against high temperature and high light in the tropics. View Full-Text
Keywords: abiotic stress; alternative carbon sources; CO2-free air; decarboxylation process; photosynthesis abiotic stress; alternative carbon sources; CO2-free air; decarboxylation process; photosynthesis
Show Figures

Graphical abstract

MDPI and ACS Style

Garcia, S.; Jardine, K.; Souza, V.F.; Souza, R.A.F.; Duvoisin Junior, S.; Gonçalves, J.F.C. Reassimilation of Leaf Internal CO2 Contributes to Isoprene Emission in the Neotropical Species Inga edulis Mart.. Forests 2019, 10, 472.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop