Pacific Plant Has Absorbed Six “Foreign” Genomes into Its Mitochondria

Amborella trichopoda, a sprawling shrub that grows on just a single island in the remote South Pacific, is the only plant in its family and genus. It is also one of the oldest flowering plants, having branched off from others about 200 million years ago. Now, researchers from Indiana University, with the U.S. Department of Energy Joint Genome Institute (DOE JGI), Penn State University, and the Institute of Research for Development in New Caledonia, have determined a remarkable expansion of the genome of the plant's critical energy-generating structures. Its mitochondria, the plant's energy-producing organelles, in an epic demonstration of horizontal gene transfer, have acquired six genome equivalents of foreign DNA -- one from a moss, three from green algae, and two from other flowering plants. It is the first time that an organelle has captured entire "foreign" genomes, those from other organisms, and the first description of a land plant acquiring genes from green algae. "It swallowed whole genomes from other plants and algae as well as retained them in remarkably whole forms for eons," said Indiana's Dr. Palmer, the senior author of the findings published December 20, 2013 in the journal Science. This work reports on the extent of Amborella's genomic gluttony. The work n the mitochondrial genome is accompanied by a report of the Amborella trichopooda nuclear genome by the Amborella Genome Project, the establishment of a high-quality Amborella trichopoda genome sequence by another group, and a Perspective piece linking the reports together. The DOE JGI Plant Program focuses on fundamental biology of photosynthesis, the conversion of solar to chemical energy, and the role of terrestrial plants and oceanic phytoplankton in global carbon cycling.