Plant pathogens and pests are the cause of substantial crop yield loss throughout the world. Damage caused by pests is estimated to be app. 100 billions USD per year despite the intensive use of pesticides. Understanding the principles of plant‐pathogen and plant‐ herbivore interactions is necessary for establishment of effective systems for plant protection. Substantial knowledge has been gathered during past decades on the mechanisms of attack/defence in one-to-one interaction studies in lab conditions. In the field, however, plants are not exposed to one type of stress only. Normally plants have to face a combination of different stresses, like drought and several types of pathogens and pests in parallel. Newly emerging tools in molecular biology and functional genomics now enable higher analytical throughput and thus more complex and realistic experimental setups.

Within the proposed project we would like to investigate a system of tritrophic interaction of potato with viral pathogen and insect pest. Potato virus YNTN (PVYNTN), causing tuber ring necrosis disease of potato (Solanumtuberosum L.), is spread all over Europe, North America and even in some parts of Asia. Since it is causing symptoms on plantlets as well as on tubers, it diminishes the crop yield and significantly lowers its quality. On the other hand, Colorado potato beetle is a major pest of potato in Europe and North America. Potato plants will be first exposed to infection with virus PVY and subsequently to larvae of Colorado potato beetle and, in parallel, to individual pathogen/pest only. Besides wild type potato plants, selected transgenic lines with perturbed major signalling pathways or with modified activitiy of critical defence components will be included. Gene expression will be measured using next generation sequencing approach, DNA microarrays and quantitative PCR. The knowledge obtained on the transcriptome level will be complemented with proteomics experiments. Data will be integrated with public knowledge using bioinformatics tools to prepare improved models/hypothesis on the studied system. Knowledge of plant‐pathogen/pest interactions will be, through the results of this study brought into new perspective, as multi-trophic interaction systems are ecologically more relevant. Potential paradigm shift in further research within this area and development of potential biotechnological applications is thus expected.