Phytochemical,biochemical, and growth changes in response to salinity in callus cultures of Nigella sativa L.

Black cumin (Nigella sativa L.) is considered as a noteworthy herbal medicine. However, no study has been conducted on the physiological adaptive mechanism of it to salinity stress, especially under in vitro condition. To this aim, the callus cultures of ten different genotypes of N. sativa were applied to evaluate the changes occurring in biochemical traits under salinity stress. The calluses were exposed to the in vitro salt stress using different sodium chloride concentrations (0, 84, and 250 mM). A reduction occurred in the content of K⁺ and callus growth by enhancing the NaCl concentration. However, most of the content of Na⁺ (4 mgg^− 1 DW), malondialdehyde (1.38 μmolg^− 1 FW), total phenolic content (1.18 mg GAEg⁻¹ FW), thymol (25.26 mgg^− 1 DW), total flavonoids content (0.06 mg QEg^− 1 FW), total flavonols (TFL) content (0.023 mg QEg^− 1 FW), total anthocyanins (Ant) (0.05 μmol g^− 1 FW) and DPPH activity (58.17%) was observed at 250 mM of NaCl. In fact, two secondary metabolites including TFL and Ant can be considered as the major contributors to the potential antioxidant activity of N. sativa at the callus level. The elicitation through NaCl opens new avenues for the selection of best dosages of NaCl for the enhancement of commercially important secondary metabolites, in superior genotypes (Nig₁ and Nig₂) of N. sativa at cellular level.