Plants' enzymic deterrent

Insect attack against a plant often triggers the release of noxious volatile organic compounds that deter the pest. Now, US researchers have demonstrated that the enzyme involved in releasing two distinct volatiles, the homoterpenes -- DMNT (4,8-dimethylnona-1,3,7-triene) and TMTT (4,8,12-trimethyltrideca-1,3,7,11-tetraene) is the same P450 enzyme used in oxidizing processes in plants, animals and bacteria. "We are excited to finally have elucidated the biosynthesis of these common plant volatiles," explains Dorothea Tholl of Virginia Tech who worked with colleagues in Germany. "The P450 protein was a long-missing enzymatic link in the formation of homoterpenes." Such insights offer the possibility of modulating a crop plant's defenses through genetic engineering and so reducing the need for pesticide sprays.