Abstract :
Systemic resistance to coflfee rust (Hemileia vastatrix) was
induced in susceptible cv, "Mundo Novoʹ by spraying
foliage with a yeast filtrate. The stages of fungal development
were compared in leaves of untreated (MN),
induced ʹMtindo Novo" (MN-Ij and coffee rust resistant
segregants ofthe hybrid ʹSarchimor" (Sch), Development
of H. vastatrix was observed at intervals of 228 h after
inoculation. The expression of resistance was detected
48-72 h after inoctilation. ln Sch, it occurred at the one
haustorial mother cell (HMC) stage, whereas in MN-1, it
occurred at the 2nd HMC stage. In Sch the majority of
aborted colonies were associated with necrotic host cells,
and the collapsed fungal hyphae exhibited a yellow autofiuorescence
which was observed in necrotic cells of the
host. In MN-1, 80% of the colonies could not be visualized
72 h after inoculation and host cells at the infection
sites were not necrotic.
