Inhibitory effect of methyl jasmonate on development of phytopathogen Alternaria alternata [Fr.] Keissl. and its reversal by ethephon and ACC

Methyl jasmonate (MeJA) was found to reduce spore germination, hyphal and mycelial growth in Alternaria alternata (Fr.) Keissl. The addition of ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC), ethylene precursor, together with MeJA to the culture medium resulted in a promotion of all developmental stages of the fungus; these compounds partially or completely reversed the inhibition due to MeJA depending on the concentrations applied. MeJA alone had no effect on ethylene production by mycelium, but after 6 days of incubation in the presence of ACC, emanation of this gas increased significantly. Ethylene is involved in reversing the inhibition of A. alternata due to MeJA.