Proteinase inhibitors offer the possibility of producing disease resistanttransgenic potatoes

Proteinase inhibitors are not only important regulators of plant endogenous proteases, but also contributors to the plant defence against insects and pathogenic microorganisms. They are normally present in plant storage organ s, but after attack by predators, their synthesis is induced throughout the plant. Proteinase inhibitors inhibit a broad range of insect digestive pro teinases and, as a consequence, reduce the growth rate and increase the mor tality rate of several insect larvae. A modern biotechnological approach of fers the possibility of enhancing the natural defence of crop plants by the transfer of genes encoding an appropriate spectrum of proteinase inhibitor s.