The effectiveness of different elicitation variants in combination with alarmone application was studied in shoot cultures of Polyscias filicifolia. The shoots were elicited with 200 µM methyl jasmonate (MeJA) or 50 µM salicylic acid (SA) alone or in combination, and their activity was compared with those treated with the alarmone diadenosine 5',5‴-P1P3-triphosphate (Ap3A), either alone or in combination with SA and/or MeJA. All treatments resulted in significant stimulation of phenolic acid production (chlorogenic and ferulic acids), as well as oleanolic acid (OA) compared to control, with their highest concentration noted under simultaneous elicitation with SA and MeJA. While the maximum content of caffeic acid was detected after treatment with alarmone alone. In each of the culture variants enhanced antioxidant activity was observed, however the level varied according to the treatment. In addition, the SA, Ap3A and Ap3A+SA variants demonstrated additional peroxidase isoforms, as indicated by Native-PAGE, as well as the highest α-tocopherol content. The highest antioxidant capacity of shoot extracts was correlated with the highest abundance of phenolic compounds and OA. The results indicate that ROS induction appears to participate in the signal transduction following Ap3A treatment.
Keywords: Polyscias filicifolia; antioxidant activity; antioxidant enzymes; diadenosine 5′,5‴-P1P3-triphosphate; elicitation; oleanolic acid; phenolic compounds; tocopherol.