Degradation of the plant defence hormone salicylic acid by the biotrophic fungus U stilago maydis

Summary Salicylic acid ( SA ) is a key plant defence hormone which plays an important role in local and systemic defence responses against biotrophic pathogens like the smut fungus U stilago maydis . Here we identified Shy1, a cytoplasmic U . maydis salicylate hydroxylase which has orthologues in the closely related smuts U stilago hordei and S porisorium reilianum . shy1 is transcriptionally induced during the biotrophic stages of development but not required for virulence during seedling infection. Shy1 activity is needed for growth on plates with SA as a sole carbon source. The trigger for shy1 transcriptional induction is SA , suggesting the possibility of a SA sensing mechanism in this fungus.