Subject: [organicviticulture] FW: Sexual Forms of 2 Helpful Fungi Are Found

From: "Lon J. Rombough" <[email-masked]>
Date: Tue, 31 Dec 2002 09:34:28 -0800

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From: ARS News Service <[email-masked]>
Reply-To: ARS News Service <[email-masked]>
Date: Tue, 31 Dec 2002 08:09:32 -0500
To: ARS News subscriber <[email-masked]>
Subject: Sexual Forms of 2 Helpful Fungi Are Found

STORY LEAD:
Researchers Find Reproductive States of Two Beneficial Fungi

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ARS News Service
Agricultural Research Service, USDA
Amy Spillman, (301) 504-1624, [email-masked]
December 31, 2002
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In the world of fungi, asexuality--that is, reproduction without sex--is not
uncommon.  Unfortunately, species that clone themselves cannot crossbreed
and improve desirable qualities.  Changes come about only through random
genetic mutations.

Now, scientists with the Agricultural Research Service and Pennsylvania
State University have found a natural solution to this problem for at least
two important fungal species.  The scientists have discovered the sexual
states, or teleomorphs, of Trichoderma harzianum and T. atroviride.

Fungi in the genus Hypocrea, often as their asexual Trichoderma states, are
useful in the biological control of costly plant diseases.  T. harzianum can
be used to control botrytis gray mold, a pathogen that causes disease in
strawberries, and it has the potential to enhance plant growth.  T.
harzianum has also been credited with degrading pesticides in soil and
preventing mycotoxin synthesis.  T. atroviride has been shown to control
snow mold fungi on winter cereals and turf grasses, and certain root rot
diseases that attack ornamentals.

Priscila Chaverri, a Penn State graduate student working with mycologist
Gary Samuels at ARS' Systematic Botany and Mycology Laboratory (SBML) in
Beltsville, Md., has identified the sexual state of T. harzianum as Hypocrea
lixii.  She confirmed it with DNA sequence analysis. Although H. lixii was
first described in the 19th century, no one had made the connection between
it and T. harzianum until now.  The journal Mycological Progress published a
paper about the discovery in August.

Meanwhile, Sarah Dodd, a Penn State post-doctoral student who is also
working with Samuels at SBML, has discovered the sexual state of T.
atroviride.  She and Samuels named the species--which is new to
science--Hypocrea atroviridis and confirmed the link through molecular
analysis.  A paper about this discovery has been accepted for publication in
the journal Mycologia.

Discovering the sexual states of two Trichoderma species suggests that more
genetic variations of these fungi exist in nature than was previously
assumed.  Plant pathologists working to develop nonchemical means to control
plant diseases may be able to use this information to find better biocontrol
agents. 

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