Abstract
Plant plastids are endosymbiotic descendants of ancestral cyanobacteria, and during evolution, they have lost most regulatory elements governing their own gene expression. Four transcription factor genes (ycf27-30) are retained in the genome of red algal plastid, while almost all regulatory factors have been lost in green plants. We recently identified four plastid RNA polymerase sigma factor genes (SIG1-4) and a histidine kinase gene (HIK) from the nuclear genome of Cyanidioschyzon merolae. Since these factors were assumed to be players for the plastid transcription regulation, expressions of these genes were monitored during acclimination to the high light condition. Northern hybridization and RT-PCR analyses revealed that the mRNAs of SIG2, HIK and ycf27 genes were transiently accumulated after the high light shift, while other transcription gene transcripts remained constant. Thus, we suggest that these gene products are involved in the high light acclimation at the transcription level.
