Polyribosome loading of spinach mRNAs for photosystem I subunits is controlled by photosynthetic electron transport

Abstract

In light‐, but not in dark‐grown spinach seedlings, the mRNAs for the nuclear‐encoded photosystem I subunits D, F and L are associated with polyribosomes and this association is prevented by the application of 3‐(3′,4′‐dichlorophenyl)‐1,1′‐dimethyl urea (DCMU), an inhibitor of the photosynthetic electron transport. To identify the cis‐elements which are responsible for this regulation, we generated a series of chimeric PsaD constructs and tested them in transgenic tobacco. The spinach PsaD 5′‐untranslated region is sufficient to confer light‐ and photosynthesis‐dependent polyribosome association onto the uidA reporter gene, while the tobacco PsaD 5′‐untranslated region directs constitutive polyribosome association. These results are discussed with regard to signals from photosynthetic electron flow which control processes in the cytoplasm.