Identification of early nuclear target genes of plastidial redox signals that trigger the long-term response of Arabidopsis to light quality shifts
Résumé
Natural illumination conditions are highly variable and because of their sessile life style plants
are forced to acclimate to them at cellular and molecular level. Changes in light intensity or
quality induce changes in the reduction/oxidation (redox) state of the photosynthetic electron
chain that act as trigger for compensatory acclimation responses comprising functional and
structural adjustments of photosynthesis and metabolism. Such responses include redoxcontrolled
changes in plant gene expression in nucleus and organelles. Here we describe a
strategy for the identification of early redox-regulated genes (ERGs) in the nucleus of the
model organism Arabidopsis thaliana which significantly respond 30 or 60 min after the
generation of a reduction signal in the photosynthetic electron transport chain. By comparing
the response of wild-type plants with that of the acclimation mutant stn7 we could specifically
identify ERGs. The results reveal a significant impact of chloroplast redox signals on distinct
nuclear gene groups including genes for the mitochondrial electron transport chain,
tetrapyrrole biosynthesis, carbohydrate metabolism and signalling lipid synthesis. These
expression profiles are clearly different from that observed in response to reduction of the
photosynthetic electron transport (PET) by high light treatments. The identified ERGs, thus,
are unique to redox imbalances in PET and were used for the analysis of potential redoxresponsive
cis-elements, trans-factors and chromosomal regulatory hot spots. The data
identify a novel redox-responsive element and indicate extensive redox control at
transcriptional and chromosomal levels that point to an unprecedented impact of redox signals
on epigenetic processes.
