Plants dynamically interact with a wide range of organisms, some of these are harmful while others are beneficial for the plant. These interactions are not only interesting objects for study, but they are also highly relevant as plant pathogens and pests destroy nearly 35% of the world’s annual crop harvest. During the theme 2 symposia two keynote speakers and junior researchers of the EPS community present their research on wild and cultivated accessions of economically important crops, such as potato, tomato, barley, tobacco and Brassicaceae, next to model species such as clover and Arabidopsis thaliana.