Changing climate likely to make 'super weed' even mor...( Researchers at the University of Del...)

Researchers at the University of Delaware have discovered a new reason why the tall, tasseled reed Phragmites australis is one of the most invasive plants in the United States.

The UD research team found that Phragmites delivers a one-two chemical knock-out punch to snuff out its victims, and the poison becomes even more toxic in the presence of the sun's ultraviolet rays.

The study, which is published in the June issue of the scientific journal Plant Signaling & Behavior, is believed to be the first to report the effects of UV-B radiation on plant allelopathy, the production of toxins by a plant to ward off encroachment by neighboring plants.

The authors include Thimmaraju Rudrappa, a former postdoctoral researcher at UD who is now a research scientist at the DuPont Company; Harsh Bais, assistant professor of plant and soil sciences; Yong Seok Choi, postdoctoral researcher in the Department of Chemical Engineering; Delphis Levia and David R. Legates, both associate professors in the Department of Geography; and Kelvin Lee, Gore Professor of Engineering and director of the Delaware Biotechnology Institute.

The research was conducted in Delaware wetlands and in Bais's lab at the Delaware Biotechnology Institute, a major center for life sciences research at the University of Delaware.

"The toxin secreted by Phragmites is degraded by sunlight -- ultraviolet rays -- and causes severe deleterious effects on other native plants," Bais said.

"Our research also addresses the growing questions of increased UV-B incidences because of global warming and its ultimate effect on plants. In this case, an invasive plant is accidentally utilizing the changed global conditions for its survival and invasion," Bais noted.

Two years ago, Bais led a study which discovered that Phragmites actively secretes gallic acid to kill off plants and take over new turf. Gallic acid, also known a
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