[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.
 
Best regards,
 
Bob
 
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>

  STORY LEAD:
  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, 
at www.ars.usda.gov/is/pr
  ___________________________________________

  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:
  http://www.ars.usda.gov/is/AR/archive/jan06/root0106.htm

  ARS is the U.S. Department of Agriculture's chief scientific research 
agency.
  ___________________________________________

  * This is one of the news reports that ARS Information distributes to 
subscribers on weekdays.
  * Start, stop or change an e-mail subscription at 
www.ars.usda.gov/is/pr/subscribe.htm
  * NewsService at ars.usda.gov | www.ars.usda.gov/news
  * Phone (301) 504-1638 | fax (301) 504-1486
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