Archivio Journal of Plant Pathology

Abstract:

Jasmonic acid, in synergism with ethylene, seems to play key roles in activating multiple resistance in various host-parasite combinations. Utilising indirect ELISA and a monoclonal antibody, changes in jasmonic acid content were studied in bean-Uromyces phaseoli combination, both compatible and incompatible, at 0, 13, 20, 42, 62 and 92 h after inoculation, in three experiments. In the susceptible cultivar ‘Bountiful’, infection with U. phaseoli induced an early, slight, but statistically significant JA increase at 13 h after inoculation, but no further significant increase. In the hypersensitive cultivar ‘Kentucky Wonder 765’, after a slight but significant JA accumulation at 13 h, larger significant increases were detected at 42 h, and a peak at 62 h (673% of the control value), coincident with the appearance of the hypersensitive flecks; at 92 h accumulation was drastically reduced. Uredospores of the fungus contained only 0.95 ± 0.11 SE ng of JA g-1 d.w. and germinated uredospores 0.46 ± 0.10 SE ng. The great JA increase detected in Kentucky Wonder 765, at the same time as appearance of the hypersensitive flecks, appear connected with a specific defensive response associated with the hypersensitive reaction.