Scientists document rare DNA transfer between animals and plants

Scientists document rare DNA transfer between animals and plants
Dr. Claudio Casola, a Texas A&M AgriLife Research forest genomics assistant professor, and his team documented a natural DNA transfer between animals and plants. Credit: Texas A&M AgriLife Communications photo



"Loblolly pine is an important economic resource across the southeastern U.S., including Texas," Casola said. "We are just now starting to understand the different parts that form the very large genome of this pine tree and other conifers.

Xuan Lin, one of Casola's doctoral students, and Dr. Nurul Faridi, leader of the U.S. Department of Agriculture Forest Service's Molecular Cytogenetics Laboratory and a collaborating faculty member, were other members of the team.

Their work, "An Ancient Trans-Kingdom Horizontal Transfer of Penelope-like Retroelements from Arthropods to Conifers," was published recently in the Genome Biology and Evolution journal.

"We called these conifer DNA sequences 'Dryads' after the Greek mythological nymphs that inhabit trees," Casola said. "Dryads are one of the many groups of DNA sequences known as DNA repeats."



He said because transposable elements make up a lot of the conifers' DNA, it is important to gather a better understanding of what they are and how they influence conifer genes and phenotypic traits.

"You can think of transposable elements as 'genomic parasites,'" Casola explained. "They spread into new genomes kind of like viruses spread between people. Unlike flu and other viral disease, these 'genomic infections' occur rarely, but once established, they can persist for millions of years."


On the other hand, Casola said, many transposable elements known as endogenous retroviruses, or ERVs, represent "DNA fossils" of retroviruses that once infected primates and other mammals.

"No less than 8 percent of our own genome is made of ERVs," he said. "Retroviruses, ERVs and other DNA repeats such as Penelope-like sequences share a unique way to make new copies of themselves."



"Dryads represent a conifer-specific subfamily within the larger family of Penelope-like retroelements, hence the manuscript's title," Casola said. "Before we described Dryads, Penelope-like retroelements were known only in animals.

"We thought that Dryads could have derived from Penelope-like retroelements that were somehow introduced into conifer genomes long ago," he said. "To confirm that, we computationally analyzed the genome sequences from 1,029 species that were neither animals nor conifers.



"One of the techniques used is called fluorescence in situ hybridization, or FISH, and allowed to visualize the position of Dryad DNA sequences on the loblolly pine chromosomes," Faridi said.


"This helped us in timing the origin of Dryads between the separation of conifers' ancestors from other plants and the radiation of modern conifer groups known to have occurred about 340 million years ago," Casola said.





"We think that Dryads changed significantly the genome landscape of ancestral conifers and possibly are still introducing important changes into the DNA of these trees," he said.

"The next step in our research will be to understand how conifer chromosomes, and especially genes, were affected by the amplification of Dryads since their invasion of these ," Casola said.


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More information: Xuan Lin et al. An Ancient Trans-Kingdom Horizontal Transfer of -like Retroelements from Arthropods to Conifers , Genome Biology and Evolution (2016). DOI: 10.1093/gbe/evw076
Citation: Scientists document rare DNA transfer between animals and plants (2016, April 14) retrieved 13 May 2021 from https://phys.org/news/2016-04-scientists-document-rare-dna-animals.html

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