Genetic engineers restore natural resistance mechanism
Neuchâtel/Halle – Swiss and German plant researchers have restored a lost natural resistance mechanism in maize plants by means of genetic engineering. Their findings, which have been filed for patent, could eventually help prevent use of insecticides like chlothianidine that kill maize pests but also bees (Pnas 106(32), 13213-13218). After Ted Turlings (University Neuchâtel) and Joerg Degenhardt (Univeristy Halle) had transferred a gene from oregano into maize, the plants began emitting the allomone
(E)-beta-caryophyllene (EbC) from their roots. The compound attracts tiny nematodes that attack and kill larvae from the Western corn rootworm (Diabrotica virgifera virgifera), the most damaging maize pest in the US.
The transgenic corn reduced numbers of Diabrotica beetles by 60%, as well as root damage in the plant. “The use of this indirect defense is an attractive strategy for increasing plant resistance to herbivores, and also for reducing the use of chemical pesticides,” said Degenhardt, who pointed out that the EbC gene could be reintroduced through breeding as well as by genetic engineering. The advantages of the biotech method, however, are that it is faster than breeding and helps prevent alteration of important traits such as yield. The researchers are now looking at the most effective ways to make use of the nematodes and their response to EbC. After decades of breeding, most commercial North American strains of maize have lost the ability possessed by maize ancestor varieties to attract the natural enemy of the Western corn rootworm through EbC emission.