Mechanical stress and lignification

Karen Snetselaar karen at athena.cs.uga.edu
Thu Apr 2 00:45:23 EST 1992


In article <kljjkbn at lynx.unm.edu> mwfolsom at hydra.unm.edu (Mike Folsom) writes:
>In article <1992Apr1.185552.27565 at doc.ic.ac.uk> ajt at doc.ic.ac.uk (Tony Travis) writes:
>>I'm interested in factors affecting the resistance of crop varieties to
>>'lodging' damage and I wondered if anyone knows if mechanical stress
>>can, itself, lead to lignification?  I know about 'stress' wood in
>>trees but don't know if more subtle changes occur in response to
>>mechanical stress such as the load from wind blowing on a canopy.
>>
I don't know of experiments that demonstrate lignification in response
to mechanical stress, but clearly plants grown where there is no wind are
very susceptible to wind damage.  On breezy days I can hardly get my
greenhouse-grown maize plants from the greenhouse into the lab without
the stems getting broken.  You could find out if lignification is involved
by comparing the amounts of lignin extracted from plants grown in still
air with amounts from plants grown with wind blowing on them.

>> [Mike Folsom]
>Have you buzzed through the plant defense literature?  Seems 
>to me that lignification is one of the mechanisms plants use 
>to defend against pathogens.  Now how different is this from the     
>production of lignin in response to mechanical stress?  I seem to 
>remember that people who do research in the area of plant 
>defense mechanisms often use mechanical techniques, e.g. 
>sandpaper, grinding powerders, etc, to induce plant responses.  
>I guess I'm wondering if the same techniques used to analyze 
>plant defense responses could be applied to the questions   
>which interest you.

Lignification is a common plant response to various abiotic 
stresses like needles sticks and abrasions as well as to pathogens
and insects.  Histological techniques are often used to document
lignin deposition.  Lignin is autofluorescent (so are some other common
cell-wall components) and there are some stains that are more-or-less
selective for lignin.  These sorts of techniques are useful for
monitoring localized lignification, but it seems to me they wouldn't
be so useful for answering your question.  The pulp and paper people 
extract lignin all the time; maybe that's the place to look for techniques. 



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