Science, Technology and Engineering

Anderson Laboratory

Department of Biochemistry

Research - Plant proteinase inhibitors and insect proteases

Female reproductive tissues and wounded leaves of the ornamental tobacco, Nicotiana alata amass high levels of serine proteinase inhibitors (NaPIs) for protection against pests and pathogens. These 6kDa inhibitors accumulate in the vacuole and are derived from multidomain precursor proteins with either four or six proteinase inhibitor domains. When incorporated into artificial diets or expressed in transgenic plants, the 6kDa inhibitors have a significant effect on mortality and growth of Helicoverpa armigera and H. punctigera larvae, the major insect pests on cotton in Australia.

We are interested in the potential of these multidomain proteinase inhibitors to enhance insect resistance in transgenic cotton, however, we are aware of the experience of others that proteinase inhibitors often fail to provide sustainable insect protection in transgenic crop plants. Consequently, we have characterised the insect proteinases that are the target for this series of trypsin and chymotrypsin inhibitors and have examined the changes in expression and activity of the enzymes after prolonged exposure to NaPIs in the diet.

Larvae that survive on diets containing the NaPIs have elevated levels of chymotrypsin that are insensitive to inhibition by the NaPIs. We are characterising the molecular features of the insect enzymes with a focus on understanding why some are strongly inhibited by the NaPIs while closely related enzymes are unaffected.

Other research interests