"Until now, we weren't able to tease these mechanisms apart, to answer questions like, why is this insect feeding less? We didn't have any tools to study these interactions in a controlled fashion."
"You could put any plant-eating insect on Arabidopsis to study this interaction from the plant side," he said. "In order to make our new model system compelling from the insect side, we had to use some tools from Drosophila genetics."
Hunting down defense genes
His team tested the Scaptomyza flies for the activity of genes known from Drosophila to be important in dealing with toxic plant compounds, and how they responded to the presence or absence of specific host plant defense molecules.
The researchers found that when they reared larvae in knockout plants unable to produce defense molecules, the flies dialed back their expression of detoxification genes.
"It makes sense for them to not turn on those genes unless the plant's defenses are up," Whiteman said.
Conversely, putting larvae on plants with intact defenses turned on their detoxification genes.
To put the new model system on a broad basis, Whiteman and his colleagues determined the genetic code of all the active genes in larvae reared on plants with different abilities to fend off insects.
"Now we have a couple of billion of base pairs of data, and our goal is to identify genes that are selectively induced or repressed in larvae depending on what kind of plant they are reared on," he said. "We found 400-500 significantly induced ones."
As often in ground-breaking research, the initial discovery stirred up a myriad of questions.
"Now we have to figure out, are those genes functionally important?" Whiteman said. "We can show that there
|Contact: Daniel Stolte|
University of Arizona