Pollutant Causes Late Bloomers

The blossoming of flowers is more than an aesthetic delight. It's a critical part of a plant's life and a key ecological cog in the intricate machinery of nature. So, it's unsettling to discover that the pollutant nitric oxide, which spews out of every car's tailpipe, also acts as a plant hormone that delays flowering in plants.

Duke biologist Zhen-Ming Pei made that discovery when he exposed the flowering plant known as Arabidopsis to nitric oxide.

Although the molecular pathways governing plant flowering have been studied intensely for decades, "nobody knew that nitric oxide was involved in these pathways," says Pei. "And nobody knew that plants would be affected by external concentrations of nitric oxide, as might be caused by air pollution."

"While our work is very much at a very detailed molecular level," he continues, "I would bet that these findings have large-scale ecological implications regarding the effects of air pollution on flowering." Pei warns that "it is entirely possible that global pollution by oxides of nitrogen could delay plant flowering worldwide."

He reported his findings in the September 24, 2004, issue of Science.