Science Daily 3.17 New thought on fungi's capabilities

[Guest guest]

" ..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 Genome

" ..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. "

" ...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. "

ScienceDaily (Mar. 17, 2010) — 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 March 18 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 " evolutionary tree " 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 genetic

change based on the interplay of DNA mutation, recombination and the effects of

selection, " said 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 Genome 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 fungi

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.