From “Genes May Travel from Plant to Plant to Fuel Evolution” (ScienceDaily, Feb. 16, 2012), we learn,
Evolutionary biologists at Brown University and the University of Sheffield have documented for the first time that plants swap genes from plant to plant to fuel their evolutionary development. The researchers found enzymes key to photosynthesis had been shared among plants with only a distant ancestral relationship. The genes were incorporated into the metabolic cycle of the recipient plant, aiding adaptation.
How this happened is unclear. But the researchers show that not only did a grouping of grasses pass genes multiple times over millions of years, but that some of the genes that were transferred became integral cogs to the plants’ photosynthetic machinery, a critical distinguishing feature in C4 plants, which dominate in hot, tropical climes and now make up 20 percent of Earth’s vegetational covering.
“As far as we know, this is the first case where nuclear genes that have been transmitted between plants have been incorporated into the primary metabolism and contributed to the evolution of a new trait, in this case C4 photosynthesis,” said Pascal-Antoine Christin, a postdoctoral researcher in the Department of Ecology and Evolutionary Biology at Brown.
“We’ve long understood how evolutionary adaptations are passed from parents to offspring. Now we’ve discovered in plants that they can be passed between distant cousins without direct contact between the species,” added Colin Osborne, an evolutionary biologist from the University of Sheffield and a corresponding author on the paper.
“What is so exciting here is that these genes are moving from plant to plant in a way we have not seen before,” said Erika Edwards, assistant professor of biology at Brown and the second author on the paper. “There is no host-parasite relationship between these plants, which is usually when we see this kind of gene movement.”
The interesting thing about lateral (horizontal) gene transfer or HGT is that the new traits come from genes contributed by an existing plant; they don’t arise through natural selection acting on random mutation (Darwin’s mechanism). That Darwin’s mechanism is the ultimate source of the swapped plant characteristics is an article of undemonstrable faith (and fierce fanaticism).
The authors hope that HGT serves as a form of rapid evolution. Surely, that’s going to depend on whether the gene can act in its new location and, if so, whether the new home finds a use for it.
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