PECTIN DEGRADING ENZYMES SECRETED BY 6 ISOLATES OF FUSARIUM-OXYSPORUM

The in vitro production of extracellular pectic activities by six isolates of Fusarium oxysporum was studied. A crude extracellular enzymic preparation can be produced from F. oxysporum with high pectic activity. F. oxysporum f. sp. lycopersici (FOL race 1) accumulated the highest levels of endo-PG activity. Other strains, F. oxysporum f. sp. lycopersici (FOL race 2) and F. oxysporum f. sp. radicis-lycopersici (FORL) reached about 20% of this activity. The PG of FOL (2D) has been characterized as exo-PG, whereas all other vascular wilt pathogens produce endo-PG. FOL strains exhibited a very similar pattern of major PG-activity in electrofocusing independent of races. One major band of activity had a pI of 7.0, and the other activity bands had pIs of 6.5, 6.15 and 5.9. One of the two FORL isolates shared the patterns of vascular wilt, the other presented a characteristic band with a pl of 7.45.