The relationship between cutinases and the pathogenicity/virulence of <I>Fusarium solani</I> in potato tubers

Abstract

Cutinase activity was spectrophotometrically determined in the culture supernatants of 40 isolates of Fusarium solani, obtained in Iran from various biological origins and grown in a minimal medium with 0.4% cutin as the only carbon source. Enzymatic activities, which ranged from 0 to 488 nmol min-1 mL-1, were related to the pathogenicity or virulence of the fungal isolates, determined on potato tubers using a 0–5 disease severity scale. Cutinase activity was either not detected at all or was very low in the non-pathogenic isolates, whereas it was directly correlated with the virulence of the pathogenic isolates (Radj 2 = 0.97), with an increase in cutinase activity of about 100 units corresponding to a one-point increase in the disease severity scale. SDS-PAGE analysis revealed that non-pathogenic F. solani isolates did not produce a cutinase band, while pathogenic isolates, with various degrees of virulence, produced single or double peptide bands with molecular weights of 20–23 kDa. We conclude that enzyme activity can be used as a predictive marker of the pathogenicity and virulence of F. solani isolates obtained from various hosts.