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A new method to determine how plants orchestrate rapid, self-protective
chemical responses should help researchers understand how crops defend
themselves from pest attacks and other stresses, August 2004 by Jim Core.

The simple and accurate method was developed by an Agricultural Research
Service scientist and his collaborators at Pennsylvania State University.
The method uses readily available chemicals, standards and instrumentation.
But no complete protocol existed until now for simultaneously analyzing the
interaction between multiple plant hormones, fatty acids, pathogen-derived
elicitors and other volatile organic compounds.

The method gives physiologists a way to examine how plants use complex
phytohormone interactions, called "signaling crosstalk," to coordinate
growth, development and dynamic responses to stress. Causes of plant stress
include insect or pathogen attacks, drought or wounds. Instead of just
looking at one or two phytohormone signals generated as a response to
stress, the method allows researchers to consider the complex signaling
networks and interactive effects of numerous plant substances involved in
metabolism.

The method was developed by Eric A. Schmelz, a plant physiologist at ARS'
Center for Medical, Agricultural and Veterinary Entomology in Gainesville,
Fla., and Penn State collaborators James H. Tumlinson and Ralph O. Mumma,
entomology professors and Juergen Engelberth, a postdoctoral fellow.

The method uses vapor phase extraction techniques to prepare and analyze
plant samples. It requires only a few milligrams of plant tissue and uses
gas chromatography to separate samples and mass spectrometry to measure
target compounds, according to Schmelz.

Additional findings are reported in the September issue of. The Plant
Journal

ARS is the U.S. Department of Agriculture's chief scientific research
agency.
[www.ars.usda.gov]

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