Cell wall degradation of Fusarium oxysporum f.sp. lycopersici race 2 by lytic enzymes from different Fusarium species for its biocontrol

The lysis of Fusarium oxysporum f.sp. lycopersici cell wall and cell wall fractions F1S (glucogalactomannan) and F4 (β-1,3-glucan chitin) was studied with lytic enzymes from 13 Fusarium species and four forms. The fungi were classified into three groups: A, fungi whose lytic enzymes do not degrade either Fol2 cell walls or F1S and F4 fractions (F. culmorum and F. solani); B, fungi whose enzymes degrade them to a very low extent after an incubation period of 72 h (F. acuminatum, F. decemcellulare, F. oxysporum, F. reticulatum, F. semitectum var. majus and F. tricinctum); C, fungi that produce enzymes that degrade Fol2 cell wall and fractions (F. equiseti, F. graminearum, F. moniliforme, F. oxysporum f.sp. gladioli, F. oxysporum f.sp lini, F. oxysporum f.sp. lycopersici, F. sambucinum and F. subglutinans). Lysis of the cell walls and fractions was followed by the release of reducing substances and by the decrease in optical density of insoluble samples (lysis degree) with the incubation time. The neutral sugars released were quantified and characterized by GLC and N-acetylglucosamine by a spectrophotometric procedure. Fusarium graminearum, F. moniliforme, F. oxysporum f.sp lini, F. oxysporum f.sp. lycopersici and F. subglutinans were selected as possible mycoparasites of Fol2 because they exhibited high hydrolytic activity on F1S fraction known to be very resistant to the enzymic lysis by other fungi, as well as on F4 fraction and isolated cell walls.