Sorts Out Signals in Stressed-Out Plants
By Jim Core
August 30, 2004
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.
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
ARS is the U.S. Department of
Agriculture's chief scientific research agency.