Monoterpene levels in needles of Douglas fir exposed to elevated CO₂ and temperature

Abstract

Monoterpene levels in current year needles of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were measured at the end of 4 years of exposure to ambient or elevated CO2 (+179 micro mol mol-1), and ambient or elevated temperature (+0.3.5;C). Eleven monoterpenes were identified and quantified using gas chromatography/flame ionization detector/mass spectroscopy, with eight of these compounds regularly occurring in all trees examined. Elevated CO2 exposure significantly reduced the levels for four of the eight main compounds in needles. Total monoterpene production was reduced by 52% (P < 0.05). Elevated temperature also reduced monoterpene levels (P < 0.07). The combination of elevated temperature and elevated CO2 resulted in a 64% reduction in total monoterpenes compared with needles on ambient temperature trees. Two-way anova showed no significant temperature-CO2 interaction. It is hypothesized that seasonal reductions in needle monoterpene pools under elevated CO2 and temperature conditions may be due to a combination of competing carbon sinks, including increased carbon flux through the roots.

The emission factor of volatile isoprenoids: stress, acclimation, and developmental responses

“…By now, some studies have reported a decrease rather than an increase in leaf monoterpene contents under elevated CO 2 (Litvak et al, 2002;Räisänen et al, 2008a;Snow et al, 2003), while other studies have reported unaffected monoterpene contents (Constable et al, 1999;Peñuelas and Llusià, 1997), overall not agreeing with theoretical predictions. For the emissions, the studies have found a non-significant effect of elevated CO 2 (Constable et al, 1999;Li et al, 2009;Llorens et al, 2009;Peñuelas and Llusià, 1997) or an increase or a decrease under high CO 2 , depending on species and time of sampling (Llorens et al, 2009).…”

Influence of abiotic stress signals on secondary metabolites in plants

“…Secondary metabolites increase in response to elevated temperatures. 60,62,63 In contrast to this Snow et al 125 reported that high temperature decreases monoterpene levels in Douglas fir (Pseudotsuga menziesii).…”

Terrestrial biogeochemical feedbacks in the climate system

“…Monoterpene metabolic production, located in the chloroplast, is rather similar to that of isoprene. Recent studies indicate reduced production and needle-tissue levels of monoterpenes in Douglas firs grown at elevated CO 2 levels 51 . Whether or not the interactive effects of temperature, photosynthetically active radiation and CO 2 (ref.…”