Shaping the life in karst: Antioxidative response of two Balkan endemic Scilla species

Scilla litardierei and S. lakusicii are closely related species endemic to the Dinarides. While S. litardierei is a characteristic species of wet meadows in karst fields, S. lakusicii inhabits open rocky habitats in the surroundings of karst fields. During their life cycle, plants in karst areas are subjected to the influence of drought, water-logging, high temperature and high intensity of light. The goal of our investigation was a comparative analysis of the isoenzyme profiles and activities of superoxide dismutase (SOD) and Class III peroxidase (POX) in the roots, leaves and flowers of S. litardierei and S. lakusicii that grew in different karst localities within their native range in the Dinarides. Field research was performed on karst fields and neighboring karst areas in eastern Herzegovina (Bosnia and Herzegovina) during the vegetation season in 2017. SODs are key enzymes in plant antioxidant defense, while POXs, in addition to their antioxidant role, play an important role in plant growth and development. The highest protein concentration in roots was measured for S. litardierei from the Lastva locality (13.416 +/- 4.213 mg/gFW), while the lowest was measured in S. lakusicii from Popovo Polje (2.516 +/- 0.565 mg/ gFW). The highest SOD activity was measured for all three plants' organs from Fatnicko Polje. The highest POX activity in leaf samples was measured in S. litardierei from Dabarsko Polje (0.6012 +/- 0.210 mu mol/mg*min), in the flower samples also in S. litardierei from Dabarsko Polje (0.288 +/- 0.005 mu mol/mg*min), while in root samples the highest POX activity was measured in S. litardierei from Fatni.cko Polje. SOD and POX isoenzyme profiles vary depending on Scilla species, locality and plant organ. According to our results, SOD and POX could play an important role in the adaptive mechanisms of Scilla species in their natural karst habitats.