Mitochondria are widely known as the “powerhouses” of the cell. They are the site of respiration and most of the energy generation in cells. What is less widely known is the other roles they play in the lives of organisms, including regulating reproductive strategies and controlling programmed cell death. Mitochondria have their own DNA and genetic system, although they rely on the nucleus for synthesis of many of their proteins.
Plant mitochondria are considerably more complex than animal mitochondria. Their genomes are much larger – some are more than one million base pairs in contrast to the sixteen thousand base pairs found in human mitochondria. Most of the extra DNA is of unknown function – there are very few extra known genes in plant mitochondria compared to other organisms. The genes of known function are among the slowest evolving known. At the same time, the genome rearranges readily and frequently and the noncoding parts of the genome are difficult or impossible to compare between species.
I am interested in the mechanisms of DNA replication, recombination and repair that maintain the mitochondrial genomes, as well as the mechanisms that allow them to expand and add so much noncoding DNA. I have proposed a model to explain the simultaneous findings of low mutation rates in genes and high rearrangement and mutation rates outside of genes. I also proposed that the non-coding DNA in plant mitochondria is functionless junk DNA.
My current work includes developing a method for transforming Arabidopsis mitochondria, as well as studying mechanisms of DNA repair in mitochondrial genomes.