Glucosylceramides from Cladosporium and Their Roles in Fungi–Plant Interaction

Cladosporium species are widely distributed filamentous fungi. One of the most important species is C. herbarum, which is related to infections in a variety of plants and of concern in plantations. Fungal cerebrosides, such as glucosylceramide (GlcCer), have been described as playing important roles in fungal growth and pathogenesis, but GlcCer from C. herbarum has not been characterized so far. For this reason, the present study aimed to elucidate the chemical structure of GlcCer from C. herbarum and its role in the interaction with Passiflora edulis. Mass spectrometry characterization of purified GlcCer revealed two major molecular ions, m/z 760 and m/z 774, and it reacts with monoclonal anti-GlcCer antibodies and is exposed on the fungal surface. P. edulis treatment with GlcCer induced increased levels of superoxide as well as the expression of some genes related to plant defense, such as PR3, POD, LOX and PAL. GlcCer also enhanced growth parameters, such as plant height and root weight. All these results suggest that C. herbarum GlcCer can stimulate plant defense mechanisms, which could help plants to face fungal infections.