A novel α-1, 3-glucan elicits plant defense responses in potato and induces protection against Rhizoctonia solani AG-3 and Fusarium solani f. sp. eumartii

All glucan elicitors from fungal cell walls have been described as ß-glucans. In a previous work, we have isolated and characterized an α-1, 3-glucan from a non-pathogenic Rhizoctonia isolate which induced glucanase activity in potato sprouts. In this work we showed that, in addition to eliciting a wide array of defense reactions, the α-1, 3-glucan induces protection against Rhizoctonia canker and dry rot in plants and tubers, respectively. The α-1, 3-glucan strongly induced ß-1, 3-glucanase and chitinase activities. Immunological analysis showed that the level of the pathogenesis-related proteins increased. Histological studies showed an increase in cell wall deposition of callose and lignin, and ultrastructural analysis showed changes in the cytoplasm and the accumulation of electron-dense bodies in vacuoles. Protection assays showed that pre-treatments of potato sprouts and potato tubers with the α-1, 3-glucan results in a 40% of protection against Rhizoctonia canker and 60% protection against dry rot, respectively.