Plants produce specialized cell wall structures, the so-called papillae, that constitute the first line of defense against appressorium-forming fungal pathogens. Papillae are remarkably strong assemblies of cell wall polymers that can resist enzymatic degradation and the extreme pressures that are exerted by the penetration peg of the fungal appressorium (O'Connell (2004) Mol Plant Microbe Interact 17, 272282). The success of the initial immune response depends on the ability of the plant to lay down sufficiently strong papillae before the appressorium is formed. Very little is known on the structural determinants of these extreme mechanical properties of the papillae and the underlying cellular processes. On the other hand, fungal pathogens most likely evolve strategies to interfere with papillae formation by producing toxins or effector proteins that target these cellular processes (O'Connell (2012) Nat Genet 44, 1060-1065). The identification of such fungal anti-defense compounds should provide interesting tools to study of the cell biological processes underlying papillae formation and may lead to new strategies for plant protection as well as sources of novel herbicides.