Method of increasing resistance to a pathogen or a pest in a plant comprising introducing into the plant and expressing therein a polynucleotide comprising a nucleotide sequence encoding a Qua-Quine Starch (QQS) polypeptide; method of producing a plant with increased resistance to a pathogen or a pest comprising crossing a plant obtained in accordance with the above method with a second plant to produce progeny plants and selecting progeny plants with increased resistance to a pathogen or a pest; a plant with increased resistance to a pathogen or a pest; a seed of the plant; a hybrid of the plant; and a seed of the hybrid plant.