Extracellular degradative enzymes produced by Rhizoctonia solani AG-3

MACHINANDIARENA, M;; WOLSKI, E. A.; OLIVA C; DALEO GR; ANDREU AB

Carlos Paz, Córdoba, Argentina

Congreso; XXXVII REUNION ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIONES EN BIOQUIMICA Y BIOLOGIA MOLECULAR (SAIB).; 2001

SOCIEDAD ARGENTINA DE INVESTIGACIONES EN BIOQUIMICA Y BIOLOGIA MOLECULAR (SAIB).

Plant pathogenic fungi produce an array of extracellular enzymes that may be important in pathogenicity. Pectinolytic and glucan hydrolytic enzymes have been isolated from a wide variety of fungal pathogens. Most attention has been focused on enzymes that depolymerize plant cell wall polysaccharides. Implication of these enzymes in pathogenesis also include the release of oligosacharides that can act as elicitors or suppressors of the plant defense response. Rhizoctonia canker is considered the most important disease of potato and is caused by Rhizoctonia solani (anastomosis group AG-3). The aim of this study was to characterize extracellular degradative enzymes produced by R. solani AG-3 that may be important as pathogenicity factors. The fungus was grown for 7 days in liquid medium with different carbon sources. Then, culture filtrates were precipitated with acetone and used for enzyme activity determination and zymograms. Using pectin as sole carbon source, secretion of polygalacturonases and methylestereases was detected. When glucose was used as carbon source, ß 1-3 and ß 1-6 glucanases were detected using laminarine and pustulan as substrates. These enzymes were partially purified and characterized and showed to be active against cell wall polysacharides from potato sprouts, the primary site of infection of R. solani. These results make these enzymes interesting candidates for further studies considering their role as pathogenicity factors.