摘要
Chloroplasts and mitochondria genomes contain a few dozen genes required for gene expression, photosynthesis, and the electron transport chain. However, proteomic and bioinformatic studies suggest that approximately 2000 and 2600 proteins are located in plant mitochondria and chloroplasts, respectively; most of them are encoded by nuclear genes, synthesized in the cytoplasm, and targeted to organelles. Despite the simplicity of organelle genomes, their transcriptional regulation is complex and can only be partially explained by currently known transcriptional machinery components, suggesting that additional unidentified regulatory factors exist （Liere et al., 2011）.
Chloroplasts and mitochondria genomes contain a few dozen genes required for gene expression, photosynthesis, and the electron transport chain. However, proteomic and bioinformatic studies suggest that approximately 2000 and 2600 proteins are located in plant mitochondria and chloroplasts, respectively; most of them are encoded by nuclear genes, synthesized in the cytoplasm, and targeted to organelles. Despite the simplicity of organelle genomes, their transcriptional regulation is complex and can only be partially explained by currently known transcriptional machinery components, suggesting that additional unidentified regulatory factors exist （Liere et al., 2011）.
