Regulatory, developmental and tissue aspects of mitochondrial biogenesis in plants

Although mitochondria play a central role in energy production in all plant tissues, the amount and activity of mitochondria differs among tissues and with development, These differences are due to the changing demands of various tissues for energy during development and the presence of different metabolic pathways in mitochondria from a variety of tissues. As mitochondria contain proteins encoded in both the nuclear and mitochondrial genomes the expression of these genomes must be coordinated. Progress has been achieved in understanding transcription of genes in both genomes. It appears from investigations to date that: i) transcriptional regulation is not a major feature of control of mitochondrial-encoded genes, and ii) the transcription of nuclear- and mitochondrial-encoded genes for proteins of a multi-subunit complex are not coordinated. Rather several post-transcriptional and/or post-translational mechanisms exist to achieve the desired coordination between the two genomes. Specific examples of the regulation of expression of mitochondrial proteins with development and among tissues are outlined which indicate the complexity of factors that interplay to achieve regulation of mitochondrial biogenesis.