Magazine article Science News

Backup Digestive Enzyme Rescues Insects

Magazine article Science News

Backup Digestive Enzyme Rescues Insects

Article excerpt

Many plants, after insects have munched on them for a day or so, produce a protein that can weaken or kill their predators by interfering with digestive enzymes called proteases. Exploiting this ability, scientists have genetically engineered experimental crops to churn out these proteins full-time. That way, insects get a dose with their first bite.

But the bugs found a way to turn the tables. Many insects survive the transgenic and normal plants, protein defenses, known as protease inhibitors.

A team of Dutch researchers say they know the survivors, secret. In response to the protease inhibitors, these insects produce a second type of enzyme that can withstand the inhibitors, assert Maarten A. Jongsma and his colleagues at the Agricultural Research Department-Center for Plant Breeding and Reproduction Research in Wageningen.

"With our transgene, we gave plants more of what they already have, but that turned out in the end not to be too clever," says coauthor Dirk Bosch.

The researchers inserted a gene from potatoes into tobacco plants, they report in the Aug. 15 Proceedings of the National Academy of Sciences. The potato gene caused the tobacco to produce protease inhibitor II (P12) continuously. P12 closely resembles the protease inhibitor that the tobacco plant produces when under attack.

The team then fed leaves from the transgenic plant, a normal plant, and a damaged one that was producing natural protease inhibitors to beet army worms, a foe of tobacco. …

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