New Method 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 Plant Journal.

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