Date: 3/31/99

Time: 10:25

Type: Symposium

Number: 235

Photorhabdus toxin complex (tc): is it an alternative for bt in transgenic crops?

*D. Bowen and R. ffrench-Constant, Dept. of Entomology, University of Wisconsin, Madison, WI 53706
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Recent concerns over insect resistance to Bt toxins being expressed in transgenic crops has led to a search for suitable alternatives. An example of such alternatives are the toxins produced by the bacterium Photorhabdus luminescens. P. luminescens is an enteric bacterium that lives in a mutualistic association with soil nematodes of the family Heterorhabditis. The bacterium can be isolated from the nematodes that carry them or from infected insects. P. luminescens is an aggressive insect pathogen which kills the host insect within 24 hours of being released by the nematode into the insects hemolymph,. Several insecticidal toxin complexes are produced by P. luminescens . The bacterium can be cultured in the absence of the nematodes or insects and will secrete the toxins into the culture broth. The toxins were purified and characterized and the genes encoding the toxins have been cloned. It was found that the native toxins were active against several insects pest including the southern corn rootworm and European corn borer. The possible uses of these toxins and further discovery of novel insecticidal toxins from P. luminescens and related bacteria will be discussed.

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