In this work, the pathogen-inducible 9-lipoxygenase (StLOX1)-pathway of potato (Solanum tuberosum) was characterized. The genes encoding the first enzyme StLOX1 and the enzyme St9DES, catalysing a subsequent step, were down-regulated in their expression by RNAinterference. Transgenic plants with strongly reduced levels of 9-oxylipins revealed no decisive role of the 9-lipoxygenase pathway for tuber development, the response to abiotic stress as well as disease development following inoculation with Phytophthora infestans, the causal agent of late blight disease, both in basal and race-cultivar-specific resistance. Furthermore, the potato SNARE-homologs (soluble NSF attachment protein receptor) StSYR1 (syntaxin-related 1) and StSNAP33 (synaptosomal-associated protein 33 kDa) were functionally characterized. Compared to control plants, RNAi plants with strongly downregulated StSYR1- and StSNAP33-expression showed an early senescence phenotype concomitant with higher endogenous salicylic acid levels. With regard to the StSYR1-RNAi plants, a higher resistance against P. infestans macroscopically correlates with enhanced necrosis formation and microscopically with a loss of papillae-formation.