This course provides knowledge on recent developments in research on plant-pathogen and plant-insect interactions. This will include the molecular targets and signal transduction pathways involved, and the ecological aspects of biotic interactions in nature and in agriculture. With regard to defense against pathogens, the innate immune response and the gene-for-gene model will be discussed in detail. The role of jasmonate and salicylate in biotic interactions will be discussed. The lectures will be illustrated by examples from ongoing research at the UvA. This includes: herbivore feeding styles, pathogenicity modes, compatibility/incompatibility, induced defenses, hypersensitive response and cell death, pathogenesis related-proteins, plant viruses, innate immunity, elicitors and (a)virulence factors, resistance-genes, hormonal signaling, jasmonic and salicylic acid, and engineered resistance. In addition, the interaction of plants with beneficial microorganisms will be discussed.