In the absence of the beetle, the mutant is virtually indistinguishable from normal corn plants, which may be why it was not discovered earlier, said Johal. Its leaves do not become vulnerable to attack by rootworm beetles until it reaches the vegetative stage, about 5-6 weeks into the growth process.
On finding the mutant, Western corn rootworm beetles scrape away the leaf tissue from the upper epidermis, resulting in a transparent “window pane” appearance. If the beetle infestation is severe, the plants can become completely defoliated, which also can reduce grain yield.A combination of structural and biochemical changes in the mutant leaves make them particularly vulnerable to attack. The cellular lobes that interlock to provide structural strength are smaller and weaker in the mutant leaves. The leaves also have substantially reduced levels of hydroxycinnmates and lignin, compounds that are responsible for cross-linking microfibers in cell walls.
Further research is being done on the possibility of using the mutant in pest control strategies and identifying the genetic pathway in normal corn plants that prevents Western corn rootworm beetles from consuming their leaves. The genes could be used to make corn plants more pest-resistant, Johal said.
The paper was published online in PLoS ONE and is available at www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0071296;jsessionid=127B91804B4E522B97208869322F0D7BFunding for the research was provided by the U.S. Department of Agriculture and the Illinois Agricultural Experiment Station.