A model coupling foliar monoterpene emissions to leaf photosynthetic characteristics in Mediterranean evergreen Quercus species

Abstract

Summary• A model was developed and parameterized to simulate monoterpene emission rates per unit leaf area (E) dependent on foliar photosynthetic potentials and activity of monoterpene synthases in the evergreen sclerophylls Quercus coccifera L. and Q. ilex L.• Assuming that total activity of monoterpene synthases controls the pathway flux, the product of leaf dry mass per unit area E was culculated as the fraction of total electron flow used for monoterpene synthesis (ε), the rate of photosynthetic electron transport (J) per unit leaf dry mass and the reciprocal of the electron cost of monoterpene synthesis. In the model, light effects on E result from light responses of J, and the temperature relationship of E combines temperature dependencies of J and the specific activity of monoterpene synthase (S S ).• Having determined J from leaf photosynthesis data and deriving an estimate of S S from in vitro laboratory measurements, good fits to diurnal time-courses of monoterpenoid emission rates were obtained using a single leaf-dependent coefficient, the total monoterpene synthase activity in the leaves.• Our analysis demonstrates that using J as a surrogate of E leads to a realistic description of E, especially under stress conditions where the previous models fail. However, analysis of daily time courses of E indicated that storage of monoterpenoids in nonspecific leaf compartments might alter the correspondence between monoterpenoid synthesis and emission rates, especially after rapid environmental change.

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

“…5 reveals a mean value of 2.4%. Niinemets et al (1999Niinemets et al ( , 2002b demonstrated that photosynthetic electron transport can be used to successfully simulate diel time-courses of isoprenoid emissions. The maximum rate of electron transport shows a strong positive correlation with the maximum rate of carboxylation and the inherent capacity of the enzyme responsible for CO 2 assimilation (Ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBP) (Medlyn, Loustau & Delzon 2002) among plant species.…”

“…Due to the high K m value of isoprene synthase, poor substrate availability due to partitioning to competing pathways may prevent isoprene synthase to be active. Even though it is questionable whether isoprenoid synthesis is ever limited by photosynthesis, as isoprenoid synthesis requires only a few percent of total photosynthetic turnover of reduced carbon, ATP and NADPH (Niinemets et al 2002b), this physiological regulation of isoprene biosynthesis would be consistent with the Carbon-Nutrient Balance Hypothesis (CNB) and/or the Growth-Differentiation Balance Hypothesis (GDB) (Litvak, Constable & Monson 2002). CNB and GDB assume that the synthesis of carbon-rich secondary compounds is limited by the availability of photosynthates (i.e.…”

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

“…The models implemented can be applied alternatively or in addition to each other (for more information see Grote, 2007;Grote et al, 2009a, b;Holst et al, 2010). In the current context the short-term isoprenoid emission models MEGAN , GUENTHER (Guenther et al, 1993), NIINEMETS (Niinemets et al, 2002a), and BIM2 (Grote et al, 2006) are coupled with models describing the canopy micro-climate within the canopy (ECM, Grote et al, 2009a) and the soil (DNDC, Li et al, 1992), photosynthesis (FARQUHAR, Farquhar and Von Caemmerer, 1982), phenology (SIM, Lehning et al, 2001;Grote, 2007), and soil hydrological conditions (QUERCUS, Rambal et al, 1993Rambal et al, , 2003) (see Fig. 1 and model descriptions below).…”

“…NIINEMETS: This model (Niinemets et al, 2002a) for isoprene and monoterpene emissions takes a more processbased approach. It links the emission rates to synthase enzyme activity (S S ) to predict the capacity of isoprenoid synthesis as well as to foliar photosynthetic metabolism via the photosynthetic electron transport rate, J , to predict substrate (Niinemets et al, 1999;Niinemets et al, 2002a).…”

Chemodiversity of a Scots pine stand and implications for terpene air concentrations

“…The empirical algorithms have been recently criticized by Niinemets et al (2010a, b), based on the missing physico-chemical controls and lack of spatio-temporal resolution in the empirical approach. Monoterpene production is controlled by temperature and light conditions, but also the CO 2 concentration and compound volatility influence either the production or diffusion from tissues, thus some process-based models taking into account these dynamic factors have been developed for isoprene and monoterpenes (Niinemets et al, 2002;Possell et al, 2005;Arneth et al, 2007;Schurgers et al, 2009).…”