A model simulating the dynamics of plant mitochondrial genomes.

Molecular evolution of the plant mitochondrial genome involves rearrangements due to the presence of highly recombining repeated sequences. As a result, this genome is composed of a set of molecules of various sizes that generate each other through recombination. The model presented simulates the evolution of various frequencies of the different types of molecules over successive cell cycles. It considers the mitochondrial genome as a population of circular molecules evolving through recombination, replication and random segregation. The model parameters are the rates of recombination of each sequence, the frequency of each type of recombination, the replication rates of the circles and the total amount of mitochondrial DNA per cell. This model demonstrates that high recombination rates lead to rapid deletions of sequences in the absence of selection. The frequency of deletion is dependent on the simulated reproductive mechanism. The conditions leading to reversible or irreversible rearrangements were also investigated.