Specific expression of the chloroplast gene for RNA polymerase (rpoB) at an early stage of leaf development in rice.

The rpoB gene for the beta subunit of rice chloroplast RNA polymerase was found to be highly expressed in unexpanded immature leaves that contained proplastids, indicating the specific expression of rpoB at an early stage of chloroplast development. A putative transcription start site (tss) was identified, but the 5' upstream region of the tss had no sequences resembling typical --35 and --10 elements. A palindromic sequence and high AT-content were recognized.