Abstract

Chloroplasts, the site of the primary reactions of photosynthesis, are organelles capable of independent protein synthesis, but which depend on the nucleus for most polypeptides. The process of photosynthesis is especially sensitive to environmental conditions and the composition of the photosynthetic apparatus can be modulated in response to environmental change. This acclimation process requires close communication between chloroplast and nucleus. Here we present evidence that the form in which carbon is exported from the chloroplast encodes information about the metabolic status of the photosynthetic apparatus which in turn controls photosynthetic acclimation.