ABSTRACT
Fusarium graminearum isolates from three different agroecological regions in Argentina were examined according to the production of different extracellular enzyme activities of potential biotechnological interest: pectinases (PGase: polygalacturonase and PMGase: polymethylgalacturonase), cellulase (CMCase: carboxymethylcellulase) and hemicellulase (xylanase). The isolates were grown in minimum salt medium supplemented with 0.25 percent glucose, 0.125 percent citric pectin and 0.125 percent oat bran as carbon sources and/or enzyme inducers. PGase activity was detected early (after two days of incubation) in all the cultures; it was found to be the highest for all the isolates. PMGase was high only for those isolates of the II region. CMCase and endoxylanase activities were particularly found at late stages (after four and seven days of incubation, respectively) and the maximum values were lower than pectinase activities.
ABSTRACT
Plant-pathogenic fungi produce an array of extracellular hydrolytic enzymes that enable them to penetrate and infect the host tissue; these enzymes are collectively called cell wall-degrading enzymes (CWDE). They may contribute to pathogenesis by degrading wax, cuticle and cell walls, thus aiding tissue invasion and pathogen dissemination. Furthermore, they can act as elicitors of host defense reaction.Fusarium head blight (FHB) is a disease caused principally by Fusarium graminearum on crops, occurring all over the world. Important economic losses on wheat-growing areas have been registered by altering quality parameters of grains. Significant progress has been made in understanding the infection process from F. graminearum on wheat, based on genomic technologies. The virulence degree of this phytopathogen on crops could arise from differences in the production of extracellular enzymes, factors controlling the establishment of infection.Fusarium graminearum isolates from different geographical areas have been examined, and a combination of morphological and molecular data allowed the division of fungi in diverse groups, which have been related to the variation in pathogenicity. In most studied cases there is a correlation between the presence of pectic enzymes, disease symptom and virulence, being also their production decisive in the infection process.
