Pectolyc Enzymes Produced by <em>Fusarium Sambucinum in vitro</em> and During Colonisation of Potato Tubers

Abstract

The ability of Fusarium sambucinum to colonise potato tubers when artificially inoculated or in liquid culture, and which pectolytic enzymes were produced and in what amounts during such colonisation were studied. Pectin lyase (PNL) activity, represented by a set of isoenzymes focalising from isoeletric point (Ip) 6.4 to Ip 9.9, was detected in the culture filtrates. The PNL time course in infected tissues was characterised by an increase in enzyme production and a differential induction of the isoenzymes. Polygalacturonase (PG) activity, represented by a single alkaline band, was detected only in the culture filtrates. Two constitutive basic pectin methylesterase (PME) isoenzymes (Ip>10.0) were also found in both the culture filtrates and the inoculated potato tissues. In rotted tissues and culture filtrates, an increase in pH to values to over 7.0 was recorded, which are values optimal for PNL activity. In the potato_F. sambucinum interaction, PNL activity was the principal pectolytic component and appeared to act synergistically with the increase in ambient pH during pathogenesis. To our knowledge, this is the first report on the involvement of pectolytic enzymes during infection with F. sambucinum.