Building the Powerhouse: What are the Signals Involved in Plant Mitochondrial Biogenesis?

With a central role in respiration and ATP production, regulation of mitochondrial form and function is essential for cell and organism survival. Our understanding of the molecular mechanisms and signaling events underlying plant mitochondrial biogenesis is limited. In a recent paper published in the Journal of Biological Chemistry we have demonstrated aspects of mitochondrial biogenesis that are dependent on an oxygen signal in the monocot model, rice. Specifically, we identified (1) a set of genes encoding mitochondrial components that are responsive to oxygen levels and (2) that a lack of oxygen represses the normal increase in the mitochondrial protein import capacity during germination, and that these changes culminate in a modified mitochondrial proteome and altered respiratory activity. These findings can be combined with an earlier study, which gave insights into the characteristics of promitochondrial structures found in dry seeds and how they change during the germination process. Together they provide evidence for regulation of mitochondrial biogenesis by developmental and environmental cues and transcriptional and post-transcriptional events. This information can be used to build a model of plant mitochondrial biogenesis within the context of seed germination and oxygen availability.