Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 28, 2002
Publication Date: N/A
Bacillus thuringiensis (Bt) delta-endotoxins, a family of crystal (Cry) proteins, are used as insecticides. We described two Bt toxins (Cry5B and Cry6A) effective at killing C. elegans. Here, we test whether Bt toxins are generally nematicidal. We analyzed the toxicities of eight Cry proteins (Cry 5A, 5B, 6A, 6B, 12A, 13A, 14A, and 21A) on five free-living nematode species (C. elegans, Pristionchus pacificus, Panagrellus redivivus, Acrobeloides sp., and Distolabrellus veechi). The results of health assays, morphology, and brood size showed four of eight proteins were nematicidal and able to kill multiple nematodes. One species was resistant to all toxins. Bt toxin was toxic to all four of the other free-living nematodes tested, including one species closely related to plant-parasitic nematodes (PPNs). Structure-function studies indicate it can be trimmed to a small, fully toxic 42 kD active core. Given its effects on many free- living nematodes and that PPNs are able to exclude large proteins from their diet, this small toxin holds promise for controlling PPNs. To test this, we are transforming Arabidopsis and tomato hairy roots with Bt toxin under control of three different promoters. Successfully transformed plant lines are being isolated and nematode infection assays are being perfected. We are growing Arabidopsis in modified Knop medium and infecting with active, sterile Meloidogyne incognita J2's. We hope to assay whether toxin expression reduces infection rates and M. incognita survival.