- United Press International, September 17, 2009 

University of Minnesota researchers said they have identified genes producing tetrahydrocannabinol, also known as THC, which is the psychoactive substance in marijuana. Studying the genes could also lead to new and better drugs for pain, nausea and other conditions, the scientists, led by Professor David Marks, said.

The researchers said they discovered the genes are active in tiny hairs covering the flowers of cannabis plants. In marijuana, the hairs accumulate high amounts of THC, whereas in hemp the hairs have little. Hemp and marijuana are difficult to distinguish apart from differences in THC.

With the genes identified, finding a way to silence them and thus produce a drug-free plant comes a step closer to reality. Another desirable step, the scientists said, is to make drug-free plants visually recognizable. Since the hairs can be seen with a magnifying glass, this could be accomplished by engineering a hairless cannabis plant.

Hemp has many industrial and commercial uses but its association with marijuana has limited its cultivation. The research appears in the Journal of Experimental Botany.