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From: riordanmr@clvax1.cl.msu.edu (Mark Riordan)
Newsgroups: sci.bio
Subject: Re: Do plants have an immune system?
Summary: Do animals?
Message-ID: <1990Apr12.013525.26488@msuinfo.cl.msu.edu>
Date: 12 Apr 90 01:14:14 GMT
References: <791@dbrmelb.dbrhi.oz>
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Reply-To: riordanmr@clvax1.cl.msu.edu
Organization: Michigan State University
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In article <7204@uhccux.uhcc.hawaii.edu>, ronald@uhccux.uhcc.hawaii.edu (Ronald Amundson) writes...
> 
>I think the question you mean to ask is "do plants have an immune
>system _like mammals_" rather than "like animals".  ....

No, plants do not have immune systems.  The mammalian immune system involves 
the production of antibodies in response to an invader (a bacterium or virus,
for example).  Plants do not produce antibodies.  There is, however, a 
"signal" that is transferred from the site of infection or injury to non-
attacked plant parts.  The nature (chemical, electrical, etc.) of this "signal"
is not known, but once the signal is 
elicited, the plant produces toxins (phenolic compounds, for example) which 
seem to protect it if further challenged by the pathogen.  This phenomenon
has been termed "induced resistance" and is the focus of several plant 
pathology labs (eg:  Ray Hammerschmidt, Mich. Ste. Univ. and Joe Kuc, Univ.
of Kentucky).