ENDO-1,3-BETA-GLUCANASE AND CELLULASE FROM TRICHODERMA-HARZIANUM - PURIFICATION AND PARTIAL CHARACTERIZATION, INDUCTION OF AND BIOLOGICAL-ACTIVITY AGAINST PLANT-PATHOGENIC PYTHIUM SPP

There were indications that endo-1,3-beta-glucanase (1,3-(1,3;1,4)-bet a-D-Glucan 3(4)-glucanohydrolase (EC 3.2.1.6)) and cellulase (1,4-(1,3 ;1,4)-beta-D-Glucan 4-glucanohydrolase (EC 3.2.1.4)) activity of Trich oderma harzianum Rifai isolate T3 were induced in sphagnum peat moss c ultivations and dual culture experiments by the presence of Pythium ul timum. Further, P. ultimum stimulated the germination of Trichoderma c onidia. Endo-1,3-beta-glucanase and cellulase were purified from T. ha rzianum isolate T3, known to control Pythium damping-off of cucumber s eedlings. The enzymes were purified from the culture filtrate of the f ungus by gel filtration and isoelectric focusing. The purified endo-1, 3-beta-glucanase was a small protein with a molecular mass of 17 kilod altons and a pi of 5.0. Two cellulases were purified to homogeneity an d had molecular masses of 40 and 45 kilodaltons respectively, and pi's of 6.4 and 7.6 respectively. Germination of encysted zoospores and el ongation of germ tubes of a plant pathogenic Pythium isolate were inhi bited by low concentrations of the purified enzymes. A strong synergis tic effect was observed on the inhibition of cyst germination by a com bination of the endo-1,3-beta-glucanase and the fungicide Fongarid. Fi nally, a time-course study of colonization of the rhizosphere of cucum ber seedlings showed that the active fungal mycelial biomass of a GUS- transformant of T. harzianum isolate T3 increased over four weeks. Tri choderma appeared to colonize healthy roofs only superficially, wherea s the mucilage of the root hairs and of distal parts of wounded areas or broken parts of the roots, were extensively colonized.