Subcellular localization of plant chitinases and 1,3-β-glucanases in Cladosporium fulvum (syn. Fulvia fulva)-infected tomato leaves

The pathogenesis-related (PR) proteins, chitinases and 1,3-β-glucanases, are thought to play an important role in the active defence of plants against various fungal pathogens. Previously we found differential accumulation of these enzymes in compatible and incompatible Cladosporium fulum—tomato interactions. Here we report the localization of chitinase and 1,3-β-glucanase in plantawith immunogold labelling techniques. The antibodies which were used, recognize both the intracellular and the extracellular isoforms of the chitinases and the 1,3-β-glucanases. In both compatible and incompatible interactions neither the host cells around the infection sites nor the intact hyphae showed a differential accumulation of chitinases and 1,3-β-glucanases. However, in incompatible interactions, degenerated material, most probably of fungal origin, was observed, which showed strong labelling with chitinase and 1,3-β-glucanase antibodies. Strong intracellular labelling was also found near protein aggregates in the plant vacuoles. Furthermore, electrondense structures of plant origin, which showed very strong labelling with both chitinase and 1,3-β-glucanase antibodies, were found in the extracellular space in incompatible interactions only.