Activity of catalase and superoxide dismutase in Lobaria pulmonaria from forest communities of middle and northernmost boreal zone (NW Russia)

The present study was carried out to evaluate the activity of antioxidant enzymes and the protein content in Lobaria pulmonaria thalli of various ontogenetic stages (studied groups: juvenile and mature) in forest communities of the middle and northernmost boreal subzones (i.e. two habitat groups). Obtained results showed that the protein content in thalli of different ontogenetic stages and habitats did not differ significantly between the two studied groups and ranged from 3.4 to 3.8 mg g-1. Peroxidase (POD) activity was low and did not exceed 0.01 µmol TG mg-1 of protein. No significant differences between the studied groups (ontogenetic and habitat) in POD was found. On the contrary, the activity of superoxide dismutase (SOD) and catalase (CAT) showed significant differences. SOD activity ranged from 5.1 to 6.3 U mg-1 of protein. Significant differences were found between the SOD activity in juvenile and mature L. pulmonaria thalli in the communities of the northern boreal subzone (p = 0.043) and in juvenile thalli from different habitats (р = 0.020). In general, CAT activity ranged from 187 to 605 μmol H2O2 mg-1 protein. Significant differences in CAT activity were apparent between the thalli from the middle and northernmost boreal subzone communities (p=0.040). The differences in CAT activity values in juvenile and mature thalli in the northernmost boreal subzone (p = 0.006) were found as well. Juvenile thalli from different habitats (p = 0.008) differed. As a result we suggest that juvenile thalli might be more suitable for the purposes of bioindication of environmental conditions, such as temperature, humidity, since they are more sensitive in comparison to mature thalli.