Establishment of biotrophy in the Ustilago maydis maize interaction

The fungus Ustilago maydis is the causative agent of maize smut disease. During this biotrophic interaction, plant defense is suppressed immediately upon penetration. We identified the secreted effector-protein Pep1. Pep1 deletion mutants failed to suppress plant defense and are not able to colonize maize tissue. Therefore, Pep1 is an essential factor for the compatible interaction between U. maydis and its host plant. Elucidation of the Pep1 function will help to understand the molecular mechanisms that determine compatibility in biotrophic plant-fungal interactions.