Transgenic Arabidopsis leaf tissue expressing a modified oryzacystatin shows resistance to the field slug Deroceras reticulatum (Muller)

Transgenic Arabidopsis thaliana has been developed which expresses the oryz acystatin mutant OC-I Delta 86, which is an inhibitor of the major proteina se present in the digestive gland of the slug, Deroceras reticulatum. When fed on leaf tissue from plants expressing this inhibitor the growth of juve nile slugs was significantly reduced by 31% compared with those feeding on control leaf tissue. Furthermore, while surviving slugs did not individuall y consume less when feeding on leaf tissue expressing OC-I Delta 86, the to tal amount of leaf tissue eaten was 50% less, due to reduced survival of sl ugs. The synthetic cysteine proteinase inhibitors E-64 and leupeptin also s ignificantly reduced slug weight gain (by at least 40%) and digestive gland cysteine proteinase activity when administered in an artificial diet, indi cating that their antimetabolic effects are due to direct inhibition of gut proteolytic activity. These results suggest that transgenic crop plants ex pressing phytocystatins could be used to suppress the growth rates of slug populations in the field.