Changes in ascorbate-glutathione pathway enzymes in response to Mycosphaerella fragariae infection in selected strawberry genotypes

Ten strawberry genotypes, resistant and moderately resistant (Joliette, Seascape, Aromas, FIN005-55 and FIN005-50) and susceptible ones (FIN00132-8, FIN00134-11, FIN00132-14, FIN005-7 and Kent) were used to assess the role of the antioxidative defence system against Mycosphaerella fragariae infection. The pathogen-induced changes of hydrogen peroxide (H2O2) and antioxidant enzymes ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) involved in the ascorbate-glutathione (ASC-GSH) cycle were examined in leaves of the selected genotypes. A significant different response was observed among the genotypes. A marked increase in H2O2 content, APX, MDHAR, DHAR and GR activities were observed in resistant and moderately resistant genotypes after inoculation by M. fragariae. In contrast, weak changes were observed in susceptible genotypes for the aforementioned enzymes and compounds. It seems that resistant genotypes capable of overproducing H2O2 have a higher capacity to scavenge and reduce the injury to strawberry leaves by regulating the ASC-GSH cycle. The results may be useful in future breeding programmes to select those individuals with high scavenging properties to breed new resistant lines. © 2011 Taylor& Francis.