Fungi can change quickly, pass along infectious ability

Mar 17, 2010
Fusarium spore
Studies done with this fungus have challenged existing beliefs about how quickly fungi can change their genetic makeup and become infectious. (Photo courtesy of Oregon State University)

Fungi have significant potential for "horizontal" gene transfer, a new study has shown, similar to the mechanisms that allow bacteria to evolve so quickly, become resistant to antibiotics and cause other serious problems.

This discovery, to be published Thursday in the journal Nature, suggests that fungi have the capacity to rapidly change the make-up of their genomes and become infectious to plants and possibly animals, including humans.

They are not nearly as confined to the more gradual processes of conventional evolution as had been believed, scientists say. And this raises issues not only for crop agriculture but also human health, because fungi are much closer on the "" to humans than bacteria, and consequently fungal diseases are much more difficult to treat.

The genetic mechanisms fungi use to do this are different than those often used by bacteria, but the end result can be fairly similar. The evolution of virulence in fungal strains that was once believed to be slow has now been shown to occur quickly, and may force a renewed perspective on how fungi can behave, change and transfer infectious abilities.

"Prior to this we've believed that fungi were generally confined to vertical gene transfer or conventional inheritance, a slower type of based on the interplay of , recombination and the effects of selection," said Michael Freitag, an assistant professor of biochemistry and biophysics at Oregon State University.

"But in this study we found fungi able to transfer an infectious capability to a different strain in a single generation," he said. "We've probably underestimated this phenomenon, and it indicates that fungal strains may become pathogenic faster than we used to think possible."

Researchers from the Center for Research and Biocomputing at OSU collaborated on this study with a large international group of scientists, including principal investigators from The Broad Institute in Massachusetts, the University of Amsterdam, and the USDA Agricultural Research Service at the University of Minnesota.

Bacteria use "horizontal" genetic transfer through chromosomes and DNA plasmids to change quickly, which is one reason that antibiotic resistance can often develop. This capability was believed to be possible, but rare, in fungi. In the new study, based on a genome-wide analysis of three Fusarium species, it was shown experimentally that complete chromosomes were being transferred between different fungal strains, along with the ability to cause infection. Various Fusarium fungi can infect both plants and humans.

In humans, fungal infections are less common than those caused by bacteria, but can be stubborn and difficult to treat - in part, because are far more closely related to animals, including humans, than are bacteria. That limits the types of medical treatments that can be used against them. Fungal infections are also a serious problem in people with compromised immune systems, including AIDS patients, and can be fatal.

According to Freitag, this new understanding of fungal genetics and evolution is great news.

For one thing, it may help researchers to better understand the types of fungal strains that are most apt to develop resistance to fungicides, and help crop scientists develop approaches to minimize that problem.

Fungal diseases are a major problem in crop agriculture, and billions of dollars are spent around the world every year to combat new and emerging fungal pathogens in plants, animals and humans.

On a more basic level, this study provides evidence that the "tree of life," with one trunk and many branches, is outdated. It should be replaced by a "network of life" in which many horizontal connections occur between different species.

Explore further: Genomes of malaria-carrying mosquitoes sequenced

Related Stories

Gamma interferon could aid fight against fungal infections

Oct 31, 2007

Interferon, the “superhero” cure for viral infections, may be a strong weapon in the battle against fungal infections in immunocompromised patients, according to an article in the November issue of Microbiology Today.

Fungi can tell us about the origin of sex chromosomes

Mar 17, 2008

Fungi do not have sexes, just so-called mating types. A new study being published today in the prestigious journal PLoS shows that there are great similarities between the parts of DNA that determine the sex of plants and an ...

Could fungal collection hold the key to new life-saving drugs?

Jun 13, 2007

Scientists may be one step closer to finding new drugs to fight MRSA, cancers and other diseases, after CABI, a leading bioservices organisation announced that its fungal collection will be screened by the University of Strathclyde.

Recommended for you

Genomes of malaria-carrying mosquitoes sequenced

Nov 27, 2014

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

How calcium regulates mitochondrial carrier proteins

Nov 26, 2014

Mitochondrial carriers are a family of proteins that play the key role of transporting a chemically diverse range of molecules across the inner mitochondrial membrane. Mitochondrial aspartate/glutamate carriers are part of ...

Team conducts unprecedented analysis of microbial ecosystem

Nov 26, 2014

An international team of scientists from the Translational Genomics Research Institute (TGen) and The Luxembourg Centre for Systems Biomedicine (LCSB) have completed a first-of-its-kind microbial analysis of a biological ...

Students create microbe to weaken superbug

Nov 25, 2014

A team of undergraduate students from the University of Waterloo have designed a synthetic organism that may one day help doctors treat MRSA, an antibiotic-resistant superbug.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.