Multivariable environmental conditions promote photosynthetic adaptation potential in Arabidopsis thaliana.

Most of our knowledge on the regulation of photosynthesis originates from studies performed in highly controlled laboratory conditions. However, in their natural habitats plants are simultaneously subjected to a broad range of abiotic and biotic stimuli which influence photosynthetic efficiency; hence there is an emerging need to examine the process of photosynthesis under multivariable field conditions in order to elucidate the mechanisms that underlie its regulation. Such knowledge has potential for providing novel targets that would improve both crop yield and performance. In the present study we compared laboratory- and field-grown Arabidopsis thaliana plants in terms of photosynthetic efficiency in modulated light intensities and CO2 concentrations. We show here that the field-acclimated plants display highly efficient photosynthesis and are more tolerant to variable light intensities and CO2 concentrations than their laboratory-grown counterparts. We also demonstrate that some structural rearrangements of LHCII and PSII, together with altered pigments composition and stomatal density, are responsible for the differences in assimilation and photochemistry. Furthermore, we employ a transcript profiling approach to explain the genetic mechanisms underlying these adaptations and suggest that they are mainly induced by the high and fluctuating light intensities which occur in the natural environment.