title: Cell wall alpha-1,3-glucans from a biocontrol isolate of Rhizoctonia: immunocytolocalization and relationship with alpha-glucanase activity from potato sprouts.
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 alpha-1,3-glucans in addition to ss-glucans. In addition, alpha-1,3-glucans are not present in plant cell walls, and alpha-glucanase activity in plants has not been described before. In a previous work, we purified and characterized an alpha-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 alpha-glucan elicitor, we prepared an antibody against the alpha-1,3-glucan and analysed its localization by TEM. Immunolocalization showed the presence of the alpha-1,3-glucan in the intercellular spaces and along the cell walls, mainly on the inner layers. This result, and the presence of the alpha-1,3-glucan in the liquid culture medium in which binucleated non-pathogenic Rhizoctonia was grown, confirmed that the alpha-glucan had been secreted. The alpha-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, alpha-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 alpha-glucanase activity was detected. Our results suggest that the presence of alpha-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 alpha-glucanolytic activity in plants.
authors: Instituto 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. ewolski@mdp.edu.ar
authors: Erika
authors: E
authors: Wolski
authors: Sara
authors: S
authors: Maldonado
authors: Gustavo
authors: G
authors: Daleo
authors: Adriana
authors: A
authors: Andreu
mesh_terms: D002473:Cell Wall / Q000737:chemistry*; D005936:Glucans / Q000032:analysis* / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D016253:Microscopy, Immunoelectron; D010572:Pest Control, Biological; D012232:Rhizoctonia / Q000737:chemistry* / Q000254:growth & development / Q000302:isolation & purification / Q000648:ultrastructure; D011198:Solanum tuberosum / Q000201:enzymology*
chemical_list: D005936:Glucans; C045788:alpha-1,3-glucan; D006026:Glycoside Hydrolases