Salicylic acid and jasmonic acid induced enhanced production of total phenolics, flavonoids, and antioxidant metabolism in callus cultures of Givotia moluccana (L.) Sreem

Givotia moluccana (L.) Sreem. is a highly valued forest tree species known for its medicinal properties and the presence of bioactive compounds. Elicitation is an effective strategy used for the biotechnological production of secondary metabolites. The study aimed at determining the effects of jasmonic acid (JA) and salicylic acid (SA) elicitation on accumulation of total phenolics, flavonoids, and regulation of antioxidant metabolism in callus cultures of G. moluccana L. Callus cultures treated with 150 µM JA for 20 d resulted in highest contents of total phenolics (81.83 mg GAE g−1 DW) and flavonoids (60.89 mg RE g−1 DW) as compared to SA-treated and control cultures. SA-treated callus cultures showed relatively higher contents of total phenolics (31.43 GAE g−1 DW) and flavonoids (38.49 RE g−1 DW) when treated with 50 µM for 5 d and 20 d, respectively, compared to control callus cultures. Treatment of callus cultures with 150 µM JA for 20 d was found to be optimal as the maximum production of H2O2 was associated with increased enzymatic (SOD, CAT, and POD) and non-enzymatic (ascorbate, total glutathione, and GSH) antioxidants that were higher than SA-treated and control callus cultures. Real-time PCR analysis of transcript levels of antioxidant genes revealed similar pattern of expression as that of enzymatic activities in SA- and JA-treated callus cultures showing correlation between transcriptional and enzyme activity regulation. On the other hand, the transcript level of PAL gene in JA-treated callus cultures was lower than in SA-treated callus although elevated enzyme activity was observed in response to JA treatment which could be due to differential posttranscriptional modifications. Overall, the study revealed that JA is more effective than SA in achieving higher yields of total phenolics and flavonoids in callus cultures of G. moluccana as well as provided insights into antioxidant metabolism in response to the treatments.