Abstract
The plastid eubacteria-type RNApolymerase (PEP) is composed of plastid-encoded core enzyme and a nuclear-encoded sigma factor, a protein for the promoter selectivity. In higher plants, a number of putative sigma factors have been identified. These multiple factors are considered to recognize different sets of promoter sequences and regulate the activity of PEP in response to the developmental stage and various environmental clues. In Arabidopsis, the accumulation of SIG5 transcripts was induced by blue light. From the run-on transcription assay using transiently Sig5 expressed protoplasts, it was revealed that this factor specifically activated the transcription of the psbD which possesses the blue-light-responsive promoter (BLRP). The genes of Sig5 exist in several plant species including rice. The accumulation of rice SIG5 transcripts was also induced only by blue light. The re-construction experiment of rice Sig5 to PEP in the wheat in vitro transcription system is in progress.
