In a finding that could fundamentally re-write science's understanding of how some parasite-host relationships work, Harvard researchers have found that, despite being separated by more than 100 million years of evolution, the parasitic "corpse flower" found in southeast Asian rainforests appears to share large parts of its genome with its host vines, members of the grapevine family.
The two plants share parts of their genome, researchers believe, through a process known as "horizontal gene transfer". As opposed to vertical transfer, in which a parent passes genes to their offspring, horizontal transfer occurs when genes are passed between organisms without sexual reproduction.
As described in the June 6 issue of BMC Genomics in a study that was co-lead with Stony Brook University, researchers found that this type of genetic sharing between these two plants is much more widespread than first suspected, and that some genes borrowed by the flowers are likely functional, and had perhaps replaced vertically inherited copies. The surprising finding, Charles Davis, Professor of Organismic and Evolutionary Biology and Curator of Vascular Plants in the Harvard University Herbaria, said, suggests that the process may convey some evolutionary advantage to the flowers, which are the largest flowers in the world.
"We found that several dozen actively transcribed genes likely originated from the flower's host," said Zhenxiang Xi, a graduate student in Davis' lab, and first author of the paper. "In addition, we found evidence that about one third of the parasites own vertically inherited genes have evolved to be more like those of hosts, suggesting that there might be a fitness benefit to maintaining genes that are more host-like."
"At the outset, we wondered if it could be that a subset of these genes might provide some defense from the host mounting an attack," Davis added. "However, the genes coming to the flowers represent
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