The present invention provides nucleic acid molecules derived from Nicotiana alata, which encode defensin-like molecules. The present invention contemplates the use of such nucleic acid molecules in the generation of transcienic plants having resistance or at least reduced sensitivity to plant pests including insects, microorganisms, fungi and/or viruses. The transcienic plants provided by the present invention include monocotyledonous and dicotyledonous plants, and particularly include crop plants and ornamental flowering plants.