Present address: US Department of Agriculture, Agricultural Research Center, Arid-Land Agricultural Research Center, Maricopa, AZ, USA.
Isoprene emission is not temperature-dependent during and after severe drought-stress: a physiological and biochemical analysis
Article first published online: 25 APR 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd
The Plant Journal
Volume 55, Issue 4, pages 687–697, August 2008
How to Cite
Fortunati, A., Barta, C., Brilli, F., Centritto, M., Zimmer, I., Schnitzler, J.-P. and Loreto, F. (2008), Isoprene emission is not temperature-dependent during and after severe drought-stress: a physiological and biochemical analysis. The Plant Journal, 55: 687–697. doi: 10.1111/j.1365-313X.2008.03538.x
- Issue published online: 7 AUG 2008
- Article first published online: 25 APR 2008
- Received 15 February 2008; revised 11 April 2008; accepted 22 April 2008; published online 6 June 2008.
- isoprene synthase;
- isoprene emission;
Black poplar (Populus nigra L.) plants grown at 25 and 35°C were subjected to drought stress to assess the combined impact of two consequences of global climate change – rising temperature and drought – on isoprene biosynthesis and emission. At both temperatures, photosynthesis was inhibited by moderate drought, but isoprene emission only decreased when drought was prolonged. The mRNA transcript level, protein concentration and activity of isoprene synthase (ISPS) changed in concert with isoprene emission during drought stress. However, ISPS activity decreased before isoprene emission during drought development, indicating a tighter control of the emission at a transcriptional or post-transcriptional level under moderate drought stress, and at both temperatures. A residual isoprene emission was measured when photosynthesis was totally inhibited after 35 days of drought. This photosynthesis-independent emission of isoprene was probably dependent on a cytosolic carbon supply as all the properties of ISPS were drastically inhibited. Isoprene emission was associated with dark respiration during the entire drought stress period, and at both temperatures, indicating that the two processes are sustained by, but do not compete for, the same carbon source. Isoprene emission was directly related to phosphoenolpyruvate carboxylase activity in plants grown at 25°C and inversely related in plants grown at 35°C, suggesting a strong temperature control on the regulation of the pyruvate flowing from the cytosol to the plastidic isoprenoid biosynthetic pathway under drought stress and recovery. In re-watered plants, the temperature control on isoprene emission was suppressed, despite complete recovery of photosynthesis and ISPS activity similar to levels in plants subjected to mild drought stress. Our results reveal the overriding effects of drought on isoprene emission, possibly affecting protein level or substrate supply. These effects may largely offset the predicted impact of rising temperatures on the emission of isoprene in terrestrial ecosystems.