Oligogalacturonides stimulate antioxidant system in alfalfa roots

Alfalfa (Medicago sativa L.) roots were treated with 50 and 100 μg cm⁻³ of oligogalacturonide (OGA) solutions with a degree of polymerization between 7 and 15. Changes in the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) as well as ascorbate (ASC) content were determined in crude extract of alfalfa roots after 30, 60 and 120 min of treatment. An increase in the SOD activity was observed in roots treated with 50 and 100 μg cm⁻³ OGA, which could be related to its O₂ ^·− scavenging function. As concern H₂O₂ scavenging, CAT activity was increased in the first 30 min by both OGA concentrations, while POX was a key enzyme at higher OGA concentration and treatment duration. ASC content firstly increased upon exposure to high OGA concentration, and then decreased after longer treatment while low OGA concentration had no effect on ASC content.