ABSTRACT
Ustilago maydis (DeCandole) Corda is a basidiomycete fungus belonging to the class Ustilaginales, the smut fungi. This group consists of plant pathogenic fungi that attack >75 families of flowering plants, both dicots and monocots [1,2]. Smut diseases of monocots are the best known since they affect cereal grains (wheat, barley, sorghum, oats, maize, rice) and other monocots of economic importance such as sugar cane. U. maydis is the etiological agent of corn smut disease, or huitlacoche (as has been known since ancient times by the inhabitants of Mexico). There are only two known hosts of the fungus [3]: maize (Zea mays L.) and teosinte (Zea mays ssp. parviglumis and ssp. mexicana). The disease is characterized by tumors that occur in all aerial plant parts. U. maydis is related to the rusts, a group of plant pathogenic fungi of the class Uredinales, and also to Cryptococus neoformans (Filobasidiella neoformans), an opportunistic pathogenic fungus of immunocompromised patients (this volume, Chapter 19 by Lengeler and Heitman). It is more distantly related to the Tremellales and to other basidiomycetes such as Schizophyllum commune and Coprinus cinereus, two homobasidiomycetes which have been extensively studied [reviewed in 4].
