We've seen this capability in a number of invasive plants that have come from Eurasia, such as garlic mustard, Bais said. The roots exude a toxin that kills native plants.
In laboratory analyses at the Delaware Biotechnology Institute, Rudrappa and Bais used activated charcoal, the material in aquarium filters, to sequester secretions from both invasive and native Phragmites plants. The charcoal attracts and traps organic chemicals.
The scientists identified the toxin produced by Phragmites as 3,4,5-trihydroxybenzoic acid. Also known as gallic acid, it is used for tanning leather, to formulating astringents.
It's nasty stuff, Bais said. If you get some of it on your skin, you definitely know it.
The toxin works, Bais said, by targeting tubulin, the structural protein that helps plant roots to maintain their cellular integrity and grow straight in the soil. Within 10 minutes of exposure to the toxin in the lab, the tubulin of a marsh plant under siege starts to disintegrate. Within 20 minutes, the structural material is completely gone.
When the roots collapse from the acid, the plant loses its integrity and dies, Bais noted. It's like having a building with no foundation--it's on its way to self-destruction.
The native Phragmites also secretes the toxin, but the exotic strain releases much higher concentrations, which could be a key to its dominance, Bais said.
Today in Delaware, stands of native Phragmites are few and far between. Bais credits Gallagher and Seliskar, who have conducted extensive research on the plant, for growing sterile cultures of the native and exotic strains for his lab tests.
This research reveals another weapon in the arsenal that Phragmites uses to overtake marshland, Seliskar said.
Screening large numbers of marsh plants to identify those that are naturally resistant to invasive Phragmites may be one ave
|Contact: Tracey Bryant|
University of Delaware