Unfortunately, the celebration didn't last long. While studying soybean plants, they discovered a new type of aphid. "We were excited about finding the resistance. We discovered this gene from Dowling and Jackson, bred it into varieties and we 'hoped that we could solve the aphid problem,' but of course things are never that simple," Diers said. "We found that there are different biotypes of soybean aphids, including a biotype that can overcome the resistance gene for Dowling."
In tests, this new aphid was able to infest Dowling as well as it could any susceptible genotype of soybean. "We don't know how widespread those aphids are or whether or not this is actually going to occur in fields, but certainly it's something to be concerned about because we know that resistance isn't going to be perfect," Diers said.
The good news is that the PI 200538 gene for resistance is different than the one in Dowling and Jackson. "We found that this second resistance gene in the PI protects the plants against this new biotype of aphid. We are currently breeding the PI 200538 gene into varieties, but it will be at least a few years before any varieties with this gene will be released."
Even after the appearance of this new aphid, Diers is still optimistic. "We have one variety with the Dowling resistance gene that's being commercialized this year. A company is increasing seed of a second variety with the Dowling gene that should be commercialized next year. So we'll have two varieties available to growers." He explained that the U of I aphid-re
|Contact: Debra Levey Larson|
University of Illinois at Urbana-Champaign