Characterization of Oligosaccharides from Rhizoctonia binucleata

WOLSKI, E. A.; ANDREU A. B; DALEO G. R; LIMA C; LEDERKREMER RM

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).

Rhizoctonia binucleate (BNR) isolate is an effective biocontrol agent for protection of potato from Rhizoctonia canker. The disease is caused by Rhizoctonia solani. The production of hydrolytic enzymes is one of the best  known inducible defense responses following microbial infection. We have shown that a cell wall oligosaccharide fraction isolated from BNR induce glucanase activities in potato sprout, the primary site of infection of R. solani. The aim of this study was to characterize cell wall BNR oligosaccharides (WOS) that may be important as biocontrol factors. WOS was purified by anion-exchange chromatography and exclusion chromatography. Analysis of WOS hydrolysates by thin-layer-chromatography (TLC) yielded a main spot coincident with standard glucose. The WOS was purified by fractional precipitation with ethanol. The 1:1 precipitate yielded 99% glucose by hidrolysis and glc analysis of alditol acetates. The optical rotation was [a]D = 195,3 (c, 0.5, water). By NMR spectroscopy it was shown that the glucan isolated has the a-configuration. A dose-response assay and a kinetic study of glucanases activities were performed. We demonstrated that both BNR mycelium and the WOS, induced glucanase activities in potato sprouts. These results show that these a -glucan may contribute to protection of the host plant against Rhizoctonia canker and may be utilized as tools for biotechnology.