Elicitation using Jasmonates, Salicylic acid, and Sodium chloride in cell suspension cultures of Justicia gendarussa Burm f.: A route for enhanced and sustainable production of apigenin and apigetrin

This study realized a high and sustained yield of apigenin and apigetrin in Justicia gendarussa cell suspension cultures by using elicitors: methyl jasmonate (MeJA), jasmonic acid (JA), salicylic acid (SA), and sodium chloride (NaCl). We cultured the leaf segments on MS basal medium with 2,4-Dichlorophenoxy acetic acid (2,4-D) at 2 mg L ^− 1 and Benzyl Adenine (BA) at 0.2 mg L ^− 1 for friable callus induction. We transferred the best-responding calli to liquid MS medium with 2,4-D at 1 mg L ^− 1 and elicited the 40th -day-old culture with varying doses of elicitors. Cultures treated with 200 µM MeJA recorded the highest accumulation of apigenin (123.98 µg g⁻¹ DW) and apigetrin (342.87 µg g⁻¹ DW) by the 2nd day of elicitation. Also, both compounds showed a significant increase upon JA elicitation, with the maximum accumulation (apigetrin 114.68 µg g⁻¹ DW; apigenin 73.93 µg g¹ DW) occurring at 100 µM JA by the 6th day. Likewise, SA at 100 µM boosted compound production (apigenin 106.57 µg g⁻¹ DW and apigetrin 231.43µg g⁻¹ DW) on day 4. Salt stress also promoted the accumulation of apigenin (107.13 µg g⁻¹ DW) and apigetrin (245.31 µg g⁻¹ DW), with the highest accumulation at 200 mM of NaCl. The elicitation capability of these four elicitors was in the order MeJA > NaCl > SA > JA. All elicitors produced higher concentrations of compounds than found in leaf extracts of field-grown plants (29.69 µg g⁻¹ DW of apigenin and 122.42 µg g⁻¹ DW of apigetrin).