Haploid cells
of U. maydis mate to form an infectious dikaryotic hypha,
which penetrates the plant epidermis and proliferates to
form large galls filled with a mass of diploid teliospores
(Banuett & Herskowitz, 1996). The unique tumor development
distinguishes smut disease symptoms from those
caused by other pathogens, and the distinct stages of disease progression provide a tool to estimate the disease severity
(Gold et al., 1997).