Rate of acclimation of the capacity for isoprene emission in response to light and temperature

Isoprene emission from plants accounts for nearly half of all non-methane hydrocarbons entering the atmosphere. Light and temperature regulate the instantaneous rate of isoprene emission but there is increasing evidence that they also affect the capacity for isoprene emission (i.e. the rate measured under standard conditions). We tested the rate of acclimation of the capacity for isoprene emission following step changes in growth conditions. Acclimation to new growth temperatures was very rapid, with most of the change occurring within a few hours and complete adjustment occurring within a day. Acclimation to new light levels was more complicated. Following a switch from low-light growth conditions to standard assay conditions (30 °C and 1000 μmol photons m^-2 s_-1), there was a rapid (5-10 min) and a slightly slower (10-50 min) acclimation of the capacity for isoprene emission. After accounting for these short-term changes, there was also a small, long-term (4-6 d) acclimation of the isoprene emission capacity to the light level of growth conditions. We found no effect of growth conditions on the coefficients used to describe the instantaneous light and temperature response of isoprene emission. Therefore, current models of isoprene emission will only need to be altered to account for changes in the capacity for isoprene emission.