[NAFEX] Fwd: Rooting for Helpful Fungi
Lon J. Rombough
lonrom at hevanet.com
Thu Jan 19 19:28:20 EST 2006
Here is a valuable reply from Dr. Robert Linderman on the ARS article
on growing your own mycorrhizal innoculant from field soil.
Begin forwarded message:
From: "Bob Linderman"
Subject: RE: Rooting for Helpful Fungi
Re: the article in Ag Research magazine. I have tried to caution
folks about the “grow your own inoculum” story that has emerged from
David Douds and colleagues in that they advocate taking raw soil and
starting pot cultures to produce inoculum on the farm. The risk is
that you can also multiply pathogens like Pythium while growing the AM
fungal inoculum. I have done that very thing trying to build up some
inoculum from field soils. Pythium is happy to ride along and grow up
with the plant roots of the pot cultures. If the Pythiums have the
advantage of being faster than mycorrhizal fungi, they will win. So,
if anyone asks you what you think, remember that caution.
Subject: Fwd: Rooting for Helpful Fungi
From: ARS News Service <NewsService at ars.usda.gov>
Date: January 19, 2006 6:32:47 AM PST
To: ARS News subscriber <lonrom at hevanet.com>
Subject: Rooting for Helpful Fungi
Reply-To: ARS News Service <NewsService at ars.usda.gov>
Learning More About Beneficial Soil Fungi
ARS News Service
Agricultural Research Service, USDA
Jim Core, (301) 504-1619, jcore at ars.usda.gov
January 19, 2006
--View this report online, plus any included photos or other images,
Beneficial soil fungi that help plants grow could become easier for
farmers to use, based on research by Agricultural Research Service
(ARS) scientists who are studying these valuable organisms.
The fungi, called mycorrhizal fungi, live inside and outside root
cells and help them reach for nutrients by extending long threads
called hyphae into the soil. The plant, in exchange, provides the fungi
glucose and possibly other organic materials that they need to survive.
Unfortunately, modern agricultural practices have reduced populations
of arbuscular mycorrhizal (AM) fungi, the most common type.
By learning more about AM fungi physiology and finding ways to grow
colonies without host plants, ARS scientists at the Eastern Regional
Research Center in Wyndmoor, Pa., hope to make the fungi a practical
option for producers.
Currently, researchers cannot cultivate an AM fungus without a host
because the fungus can't complete its life cycle without the organic
nutrients or other stimuli it receives from roots. Gerald Nagahashi, a
chemist/cell biologist at ERRC, has been focusing on the events that
must occur before the fungus can colonize a host plant.
He developed a bioassay showing that host root components--including
chemical compounds exuding from the roots, root caps and root border
cells--induce fungal hyphal branching. The increase in branching
creates a greater potential for the fungus to find and attach to the
host root surface.
Nagahashi and David D. Douds, an ERRC microbiologist, investigated how
environmental factors, such as chemical compounds from host roots, blue
light from the sun’s spectrum, and carbon dioxide, affect AM fungal
growth, either individually or together.
Their techniques involved growing host roots in sterile culture and
using sterile fungal spores to study various environmental factors
individually or in combination. They found that these three
factors--root chemicals, blue light and carbon dioxide--can all work
independently to promote growth in AM fungi but are even more effective
when applied together.
Read more about this research in the January 2006 issue of
Agricultural Research magazine, available online at:
ARS is the U.S. Department of Agriculture's chief scientific research
* This is one of the news reports that ARS Information distributes to
subscribers on weekdays.
* Start, stop or change an e-mail subscription at
* NewsService at ars.usda.gov | www.ars.usda.gov/news
* Phone (301) 504-1638 | fax (301) 504-1486
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