Research Could Lead to Environmentally Friendly Pest Control

Working on enzymes that could lead to environmentally friendly pest control, from left to right are: Dong-Sun Lee, Ph.D., and C.S. Raman, Ph.D., both with UT Houston; and Pierre Nioche, Ph.D., Universite? Paris Descartes.

Would you like a lemony watermelon? How about a strawberry-flavored banana? Biochemists at The University of Texas Medical School at Houston say the day may come when scientists will be able to fine tune enzymes responsible for flavors in fruits and vegetables. In addition, it could lead to environmentally friendly pest control.

In the advance online publication of Nature on Aug. 20, UT Medical School Assistant Professor C.S. Raman, Ph.D., and his colleagues report that they were able to manipulate flavor enzymes found in a popular plant model, Arabidopsis thaliana, by genetic means. The enzymes- allene oxide synthase (AOS) and hydroperoxide lyase (HPL)-produce jasmonate (responsible for the unique scent of jasmine flowers) and green leaf volatiles (GLV) respectively. GLVs confer characteristic aromas to fruits and vegetables.

Green leaf volatiles and jasmonates emitted by plants also serve to ward off predators. "Mind you plants can't run away from bugs and other pests. They need to deal with them. One of the things they do is to release volatile substances into the air so as to attract predators of the bugs," Raman said.

"Genetic engineering/modification (GM) of green leaf volatile production holds significant potential towards formulating environmentally friendly pest-control strategies. It also has important implications for manipulating food flavor," said Raman, the senior author. "For example, the aroma of virgin olive oil stems from the volatiles synthesized by olives. By modifying the activity of enzymes that generate these substances, it may be possible to alter the flavor of the resulting oils."

According to Raman, "Our work shows how you can convert one enzyme to another and, more importantly, provides the needed information for modifying the GLV production in plants." The scientists made 3-D images of the enzymes, which allowed them to make a small, but specific, genetic change in AOS, leading to the generation of HPL.

The study dispels the earlier view that these flavor-producing enzymes are only found in plants, Raman said. "We have discovered that they are also present in marine animals, such as sea anemone and corals. However, we do not know what they do in these organisms."

The research is supported by Pew Charitable Trusts through a Pew Scholar Award, The Robert A. Welch Foundation, By Rob Cahill, Institutional Advancement The National Institutes of Health, a Beginning Grant in Aid from the American Heart Association, and an INSERM Avenir Grant sponsored by La Fondation pour la Recherche Medicale.

By Rob Cahill, Institutional Advancement

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