Cis Information Regulating the Functions of Chloroplast Dependent on Environmental and Developmental Cues
-- In vivo Analysis by Means of Chloroplast Transformation --

Most of plastid promoters transcribed by eubacterial-type plastid RNA polymerase ( PEP ) are reminiscent of σ70 promoters in E.coil comprising of the -35 and -10 elements. In vitro transcription experiments have demonstrated that the -35 element was not essential for initiation of transcription at the psbA promoter in some plants, dependent on the developmental stage of plastids. By using transplastomic approach, however, we found that major transcription activity at the psbA promoter required the -35 element in all types of tissues in tobacco. In addition, we found that the gfp mRNA from the wild type psbA core promoter ( -41 through +7 ) accumulated preferentially in leaf tissue in a similar manner as the native psbA mRNA, suggesting that no sequence outside of the promoter core contributed to the leaf-specific psbA promoter function.
Stromules protruding from the surface of chloroplasts was visualized in transplastomic plants expressing GFP in chloroplasts. We found that they were induced various stresses, such as drought, salt, osmotic and mechanical stresses.
Furthermore, we revealed that the movement of stromules is dependent on cytoplasmic actin filaments, but unidentified structures in chloroplasts may be involved in the maintenance of their structure.