Cell wall α-1,3-glucans from a biocontrol isolate of Rhizoctonia: immunocytolocalization and relationship with α-glucanase activity from potato sprouts |
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Authors: | Erika Wolski Sara Maldonado Gustavo Daleo Adriana Andreu |
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Institution: | aInstituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Fúnes 3250 4to nivel, P.O. Box 1245, Mar del Plata, Argentina;bLaboratorio de Anatomía y Embriología Vegetal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, P.O. Box. 1428, Buenos Aires, Argentina |
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Abstract: | The interface between plants and pathogens plays an important role in their interaction. Studies of fungal cell walls are scarce and previous results show the existence of α-1,3-glucans in addition to ß-glucans. In addition, α-1,3-glucans are not present in plant cell walls, and α-glucanase activity in plants has not been described before. In a previous work, we purified and characterized an α-1,3-glucan from a binucleated, non-pathogenic Rhizoctonia isolate, which induces plant defence responses. Therefore, in order to study the architecture of the fungal cell wall, and the accessibility and localization of the α-glucan elicitor, we prepared an antibody against the α-1,3-glucan and analysed its localization by TEM. Immunolocalization showed the presence of the α-1,3-glucan in the intercellular spaces and along the cell walls, mainly on the inner layers. This result, and the presence of the α-1,3-glucan in the liquid culture medium in which binucleated non-pathogenic Rhizoctonia was grown, confirmed that the α-glucan had been secreted. The α-1,3-glucan was also immunocytolocalized on potato sprouts tissue elicited with the glucan; gold particles were observed in vacuoles and close to the plasmalemma. In addition, α-glucanase activity in potato sprouts was detected using cell wall glucans from the pathogenic isolate R. solani AG-3 as substrates; whereas, when cell wall glucans from non-pathogenic isolates were used, no α-glucanase activity was detected. Our results suggest that the presence of α-1,3-glucans could be associated with the formation and integrity of the cell wall and also with plant–fungi interactions. This is the first report to describe α-glucanolytic activity in plants. |
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Keywords: | Immunoelectron microscopy Non-pathogenic binucleate Plant-fungus interactions Solanum tuberosum Ultrastructure |
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