Many features of an organism are influenced by clues from the environment of the organism. These features are called phenotypic plastic features and are important for an organism to deal with unpredictable environments.
But which genetic mechanisms underlie these characteristics?
Jennifer Brisson, a professor of biology at the University of Rochester, and her former postdoctoral researcher Benjamin Parker, today Assistant Professor of Microbiology at the University of Tennessee, phenotypically studied plastic features of pea aphids and uncovered genes that affect aphids Respond to their environment produce wingless or winged offspring. In a recent article in the journal Current Biology the researchers examine how phenotypic plastic features develop and address critical questions about the development of environmentally sensitive features.
Pea aphids are insects that reproduce rapidly and typically yield offspring that have no wings. As many gardeners know, aphids can quickly overwhelm and kill the host plants they live on and feed on. When an environment is crowded with other aphids, the females begin to produce progeny that have wings rather than the typical wingless offspring. The winged offspring can then fly to new, less crowded plants and colonize them.
"Aphids have been doing this trick for millions of years," says Brisson. "But some aphids are more sensitive to repression than others, so to understand why this textbook example of phenotypic plasticity works, it is crucial to find out."
The researchers used evolutionary genetics and molecular biology techniques to identify genes that determine the degree of aphids reacting to crowding. Surprisingly, the genes found are from a virus, which was then taken up in the aphid. The virus, which comes from a group of insect viruses, the so-called Densoviruses, causes its host to produce offspring with wings. Researchers believe that the virus does this to facilitate its own dissemination. As Brisson and Parker noted, the gene from the virus has the same function of producing winged progeny even after it has been transferred and incorporated into the aphid genome.
"This is a novel role for viral genes that are co-opted by the virus genome for other purposes, such as the modulation of plastic phenotypes," says Parker. "Microbial genes can be incorporated into animal genomes, and this process is important for evolution."
The most lateral DNA DNA inherited from other organisms, such as viruses, is not expressed by their hosts because it rapidly inactivates or eliminates. However, in most organisms – including humans – there are examples where genomes co-optic genes sideways. For example, in humans, the gene that forms a membrane between placenta and fetus has been co-opted from a retrovirus.
Brisson and Parker found a clear case in which genes from outside an organism were co-opted by the organism to alter the strength of a plastic response to environmental influences. Microbial genes such as those of viruses can therefore play an important role in the evolution of insects and animals, says Brisson. "Even in old traits like the one we're studying, new genes can play a role in shaping plastic features and help organisms deal with an unpredictable world."
Researchers discover interactions between plant- and insect-infecting viruses
Benjamin J. Parker u. A. A laterally transmitted virus gene alters the plasticity of aphids, Current Biology (2019). DOI: 10.1016 / j.cub.2019.05.041
Virus genes help determine if aphids get their wings (2019, June 14)
retrieved on 16 June 2019
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