Induction of Ustilago maydis Appressorium and Filamentation.

Ustilago maydis is a model smut-causing fungus infecting maize. Two compatible mating-type isolates of the fungus must form the infectious dikaryotic filaments that form infection. However, several laboratory techniques and strains have been developed that can induce this phenotype under controlled conditions, in order to study the pathogen outside the complexities of the host and microbiome. Three such methods are described here, which cover the use of charcoal-supplemented agar to induce filamentation, appressorium formation on hydrophic surfaces with 16-hydroxyhexadecanoic acid, as well as inducing b-dependent filamentation in liquid culture with engineered strains.