Who would expect that the story of one of the oldest plants in the world is a tale filled with sex and gluttony? Yes, survival of the oldest known flowering plant (Amborella trichopoda) is not necessarily the result of rain, but instead of organelles (the nuclei of its cells) and mitochondrial DNA (the section of the cell related to converting food to energy).
The plant is a woody shrub from deep in the jungles of the South Pacific…New Caledonia, to be specific. What’s most unusual is that some 200 million years ago, several hundreds of thousands of flowering plants came into being and populated the planet. Of those now-extinct plants, an ancestor of this particular one survived. Why? It was a question that dominated the thoughts of one of the most famous scientists ever: Charles Darwin.
Amborella Genome Project and its findings
A group of modern-day researchers from around the world took up the mystery that beleaguered Darwin and took several years to map the genome of this ancient plant. Their findings, recently published in the journal, Science, resulted in some interesting findings about the plant and its ability to adapt.
A big appetite and the doubling of genomes
Among those is that within the plant’s genomes are organelles from four other distinct plants (three species of moss and one of algae). Many plants have parasitic organisms, such as moss or algae, that latch on or grow around a plant like the Amborella trichopoda; however, for the Amborella trichopoda, it literally consumed these other plants, taking them in and making them a part of its own DNA. (In most cases, plants would seek to shed the parasitic hangers-on.)
According to Indiana University Professor Jeffrey Palmer, the study here “will help bring mitochondrial sex out of the closet.” In addition, notes the Guardian Liberty Voice, “Though the Amborella trichopoda contains the entire genomes of four other plant species, it also contains the foreign DNA of two other plant species, making a total of almost six whole genomes existing within the genome structure of one plant.”
For a typical plant, there might be about 500,000 mitochondrial genome base pairs. In the case of the Amborella trichopoda, there is an “incredible 3.9 million base pairs,” notes the Guardian. This doubling (or more) of the genomes helps explain the evolution of flowering plants and the development of floral organs.
Real significance, a living fossil record
What makes this plant so unusual, notes the Los Angeles Times, is that it provides a historical record of the types of plant life that came before. Notes the Times: “The plant’s mitochondria thus retain a kind of fossil record largely absent in other plant species. The foreign DNA amounts to about six genomes, the researchers believe, four of them acquired in whole.” Scientists also note that no fungi contributed to the plant, spurring the belief that mitochondrial fusion of fungi comes by different process than found in green plants.
Or the plant that didn’t burst
For the Los Angeles Times, the best analogy is the children’s song of the old lady who swallowed a fly (and a spider, cat, dog and horse, only to burst at the end of the song). For the Ambrorella trichopoda, it took on all those other plant genomes, but “The Amborella didn’t burst. It swelled to an enormous size and is just stuck with all this extra DNA.” Or, in the words of the Guardian, “Besides being one of the oldest species of flowering plants, this flowering shrub is also one of the sexiest and hungriest plants ever discovered.”