What Happens to the Pollen’s Organelle DNA?

Our plant breeder finds the answer in a research paper that, conveniently, studied different species of lilacs.  Researchers found that when the pollen grain was first forming from a cell it contained numerous mitochondria and chloroplasts.  As the plant further developed these cells into pollen grains, certain species removed half of the mitochondria and all of the chloroplasts.  Then, if that wasn’t enough, it degraded up to 97% of the remaining mitochondrial DNA, which means the final pollen grain does not contain much organelle DNA to be passed on from the father’s side.  Finally, the egg also has a gatekeeper.  As a pollen grain enters the egg, the egg shuts out everything but the nuclear DNA of the pollen (Mogensen 1996).  This leaves the very small amount of remaining organelle DNA outside the egg, meaning the resulting offspring will only inherit maternal organelle DNA.