Characterization of Superoxide Dismutase from the Potato Cyst Nematode, .

Potato cyst nematodes (PCNs), such as and , are some of the most agriculturally and economically important pests of potato. Upon nematode infection, a principal component of plant defense is the generation of the reactive oxygen species (ROSs). ROSs are highly toxic molecules that cause damage to pathogens and host alike. To infect the plant, nematodes protect themselves from ROSs by activating their own antioxidant processes and ROS scavenging enzymes. One of these enzymes is a superoxide dismutase (SOD; EC 1.15.1.1), which prevents cellular damage by catalyzing conversion of the superoxide radical (O) to hydrogen peroxide (HO) and molecular oxygen (O). We have isolated a putatively secreted isoform of a Cu-Zn SOD () from and localized the expression of this gene in the posterior region of the nematode. Furthermore, we studied the expression of the gene during early parasitic stages of infection (24 to 72 h) in the susceptible potato cultivar Desiree, the resistant potato cultivar Innovator, and an immune host, . The gene was significantly upregulated, regardless of the host type; however, the expression pattern differed between the susceptible and the resistant or immune hosts. This finding suggests that gene is responding to infection in plant roots differently depending on whether the nematode is experiencing a compatible or an incompatible interaction.