Thursday, Mar. 11, 2010
Ferns began to evolve some 400 million years ago during one of Earth’s first greening periods. Early sharks and giant sea scorpions swam the oceans, present-day Utah was underwater and a volcanic archipelago slammed into North America’s then-West Coast to form Nevada’s Antler Peak. Ferns subsequently shared the landscape with flowering plants yet diverged sharply from their seed and flower-producing kin. The curious plants reproduce not by seed but via tiny spores dispersed by the wind.
Utah State University biologist Paul Wolf studies the ancient plants and believes the time is ripe to apply modern-day genomics to crack the fern’s genome. His research, conducted in collaboration with Michael Barker of the University of British Columbia and University of Arizona, is described in the article “Unfurling Fern Biology in the Genomics Age” published in the March 11, 2010 issue of BioScience.
“Biologists have developed genomics using model organisms, such as the fruit fly, mouse and corn, to further our knowledge of life, and each has been the starting point of critical breakthroughs,” says Wolf, professor in USU’s Department of Biology and Ecology Center. “But we’re at the stage where genomic applications are being applied to the rest of the tree of life and the science is shifting to plants beyond crops.”
Ferns share ancient history with flowering plants, he says, so discerning how they evolved and their genetic makeup could have important implications for understanding all members of the plant kingdom.
“This kind of comparative approach provides context, which is needed to address questions about all land flora,” Wolf says. “Knowledge of ferns’ basic biology and evolutionary history is essential if we are to make appropriate inferences about seed plants, including the economically and nutritionally important flowering plants.”
Some 12,000 species of ferns have been identified and scientists began to study their genetics nearly 70 years ago.
“Studies of ferns in the 1940s and ‘50s focused on chromosomes,” Wolf says. “Ferns have a startlingly high amount of chromosomes and scientists wanted to know why.”
Some species of ferns, he says, have genomes — full sets of chromosomes — that are ten times the size of human genomes.
As the study and tools of genomics developed in the latter half of the 20th century, biologists temporarily shelved questions about fern chromosome numbers and shifted their focus to a few of the plant’s newly identified genes. With recent advances, however, scientists are poised to explore the full genome and revisit questions of ferns’ genetic complexity.
“I feel like we’ve come full circle,” Wolf says. “Only now we’re getting back to questions about ferns’ chromosomes.”
Among those inquiries: how many times, in the course of evolutionary history, has the fern genome “doubled” or duplicated its chromosomes?
“Not as many times as one might expect from an organism with so many chromosomes,” Wolf says. “This has been a surprise.”
He and Barker surmise that ferns may possess a different process for streamlining their genomes than other plants.
“Organisms, both plants and animals, typically have a mechanism for weeding out redundant genetic material as genes are duplicated,” Wolf says. “It’s possible that ferns don’t have this mechanism, which is another key reason why these plants make an ideal model for genomic study.”
The sheer size of fern genomes will also provide a robust test for emerging genomic sequencing technologies, he says.
“If you can sequence a fern, you can sequence anything.”
Writer: Mary-Ann Muffoletto, 435-797-3517, email@example.com