Modeling of annual variations of oak (Quercus robur L.) isoprene synthase activity to predict isoprene emission rates

Strong correlation between isoprene emission and gross photosynthetic capacity during leaf phenology of the tropical tree species Hymenaea courbaril with fundamental changes in volatile organic compounds emission composition during early leaf development

“…This indicates that only the inherent capacity of the plant to synthesize isoprene changes during leaf development, but not the instantaneous dependence on driving environmental factors. In temperate plant species maximum values of the activity of isoprene synthase were found when the contents of photosynthetic pigments reached their summer plateau (Lehning et al 2001), and photosynthetic electron transport was proposed to exert primary control over iso- prenoid synthesis in process-based model approaches by Niinemets et al (1999Niinemets et al ( , 2002a and Zimmer et al (2000). This is in general agreement with our observations, as highest isoprene emission rates were observed when the photosynthetic capacity reached its maximum in mature leaves investigated in the dry season (Table 1).…”

“…Control of production and emission is shared among different factors and it is obvious that their relative importance also varies with leaf phenology. Previous studies have emphasized the essential function of isoprene synthase enzyme activation in regulating isoprene biosynthesis and emission Lehning et al 1999;Lichtenthaler 1999;Lehning et al 2001). More recent investigations focused on the regulatory role of the availability of its substrate DMAPP (Brüggemann & Schnitzler 2002a, b;Rosenstiel et al 2002), or other intermediates and enzymes of this biosynthetic pathway (Brüggemann & Schnitzler 2002c;Wolfertz et al 2003).…”

Process-based simulation of seasonality and drought stress in monoterpene emission models

“…However, there are only two models known to the authors that explicitly account for the cumulative effect of both impacts temperature and radiation, throughout longer time periods. One is the respective routine of the MEGAN model Müller et al, 2008), which applies an empirical adjustment based on the past 10 days of light and temperature to calculate emissions, and the other is the SIM model that derives the seasonal course of the isoprenoid forming enzyme activity, which is closely related to potential emission, explicitly from the previous days climatic conditions (Lehning et al, 2001). Only the latter model reflects the finding that seasonal changes in enzyme activity result from physiological production and destruction processes (Lehning et al, 1999;Loreto et al, 2001;Fischbach et al, 2002;Mayrhofer et al, 2005).…”

“…However, seasonal dynamics driven by phenology, enzymatic activity, or drought stress strongly modify annual ecosystem emissions. Although these impacts depend themselves on environmental conditions, they have yet received little attention in mechanistic modelling.In this paper we propose the application of a mechanistic method for considering the seasonal dynamics of emission potential using the "Seasonal Isoprenoid synthase Model" (Lehning et al, 2001). We test this approach with three different models (GUENTHER, Guenther et al, 1993; NI-INEMETS, Niinemets et al, 2002a; BIM2, Grote et al, 2006) that are developed for simulating light-dependent monoterpene emission.…”

“…In this paper we propose the application of a mechanistic method for considering the seasonal dynamics of emission potential using the "Seasonal Isoprenoid synthase Model" (Lehning et al, 2001). We test this approach with three different models (GUENTHER, Guenther et al, 1993; NI-INEMETS, Niinemets et al, 2002a; BIM2, Grote et al, 2006) that are developed for simulating light-dependent monoterpene emission.…”