CRC/TRR 175/3: Mechanisms and components of GUN1/GLK signalling and its relevance for acclimation (SP C05)

The chloroplast PPR protein GUN1 integrates three different pathways of retrograde signalling in the chloro-plast. The only other protein with a similar coordinative role in GUN signalling is GLK1, a nuclear transcription factor (TF). It remains unclear how signals are relayed from GUN1 in the chloroplast to the GLK1 TF in the nucleus and beyond. In the next funding period, we will continue the analysis of the factors identified in the previous funding period. Concurrently, we shall dissect in detail the molecular regulatory programmes that control GLK1 activities, using a combination of genetic, imaging and biochemical analyses of candidate TF activities, and exploiting the observed natural variation in GLK1 activities across natural accessions. Additionally, we shall draw on the natural diversity in GLK1 activities among natural accessions to understand the regulation of GLK1 during acclimation in Brassicaceae by applying molecular evolutionary methods designed to assess regulatory element conservation in the GLK1 promoter. (shortened)