The sequencing of the genome of the amborella trichopoda (photo ©Scott Zona) helped solve the mystery of the appearance of flowering plants during the Cretaceous. Charles Darwin called it an abominable mystery due to the difficulty of understanding how plants evolved to result in the birth of the flowers. The Amborella Genome Project, which also published online the DNA sequences of this plant, has uncovered a horizontal gene transfer from other organisms.
The Amborella trichopoda is an angiosperm plant endemic to the rainforest of New Caledonia. It’s considered a living fossil because it’s the only existing species of the family Amborellaceae, appeared about 130 million years ago. It’s considered the ancestor of all angiosperms, meaning the plants that reproduce thanks to the flowers and to understand the its origins its DNA was sequenced.
An international team that includes researchers from the Institute of Research for Development of New Caledonia but also scientists from Indiana University and the Pennsylvania State University has sequenced and analyzed the DNA of the amborella trichopoda to understand the origin of flowers. This research has led to the discovery that this plant was born by absorbing genes from other species, including entire mitochondrial genomes of three species of green algae and one moss.
Horizontal gene transfer, which is the transfer of genetic material to another not descending cell, is a normal phenomenon in bacteria and viruses. Among plants, but also among animals, it can happen and its mechanisms are still being studied by evolutionary biologists. It’s been recognized as a possible factor of evolution and the case of the amborella trichopoda seems really exceptional.
This plant was born thanks to a multiplication of its DNA caused by the absorption of a significant amount of chromosomes from other species. Much of this DNA has become junk and yet the resulting organism didn’t die and indeed thrived in a unique way creating a huge lineage of plants.
Modern genetic technologies are making it possible to understand much better than before the mechanisms of evolution. It’s possible that other significant evolutionary leaps have been made possible thanks to a horizontal gene transfer by absorbing DNA from other species, including viruses that attacked a certain organism. The research in this direction are probably just beginning.
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