The rpo genes encode the subunits of an eubacterial- like RNA polymerase in plant chloroplasts. Genes which play a central role in plastid function are normally slow to evolve but in the family Geraniaceae, however, the rpo genes appear to be evolving at a faster rate than are the other plastid genes. In the species Pelargonium hortorum, the rate of evolution seems to be strikingly higher. The goal of this research is to understand the extent of constraints on and the mechanisms responsible for the strikingly accelerated evolution of these genes. Specifically, (1) the rpo genes from Pelargonium will be sequenced (2) the promotor regions of other plastid genes will be examined to determine if they have changed at a similar rate and (3) the possibility of RNA editing will be investigated by sequencing cDNAs of the rpo genes. %%% The results of this work will contribute to our understanding at the level of the genome of the constraints and enhancers affecting the rate of evolutionary change.
