Inoculation by F. verticillioides and U. maydis was effective
in establishing infection. We randomly sampled leaves from
20 plants in the F. verticillioides-only treatment at 24 h after
inoculation, and recovered F. verticillioides from 19 out of 20
surface-disinfected leaves. Neither of the endophytic F.
verticillioides isolates, FV1 or FV2, caused disease symptoms
such as leaf blight or wilting, nor did F. verticillioides
inoculation alone affect plant height. The level of infection
by U. maydis was high, 60% overall, and similar to that
observed in field studies (Baumgarten et al., 2007) and in
our other greenhouse studies. Lesions due to U. maydis
infection were visible as early as 2 days after inoculation as
small leaf tumors, followed by stem tumors later in disease
development. Although some plants developed stem tumors
without showing earlier leaf disease symptoms, the development
of smut disease symptoms and progression of disease
through time was even across plants; 82.4% of U. maydisinfected
plants formed small stem galls by DAP 19. Most
infected plants died between DAP 25 and 30. Plants without
U. maydis inoculation did not exhibit smut disease symptoms.