The present invention provides genetic molecules encoding plant floral defensin-like molecules and their use in generating transgenic plants having resistance or at least reduced sensitivity to plant pests including insects, microorganisms, fungi and/or viruses. The present invention further provides for the use of floral- and seed-derived defensins in the generation of insect resistance in plants. The plants may be monocotyledonous or dicotyledonous plants and are in particular, crop plants and ornamental flowering plants. The genetic molecules are also useful in generating recombinant defensin-like molecules for use in the topical application of compositions to prevent or otherwise retard pest-infestation of plants. The floral defensin-like molecules or genetic molecules encoding same of the present invention may be used alone or in combination with other agents such as a proteinase inhibitor precursor or a nucleic acid molecule encoding same or other molecules or their encoding nucleotide sequences. 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.