Elicitation of flavonoid biosynthesis in cell suspension cultures of Haplophyllum virgatum by sodium nitroprusside

Plant cell suspension culture, along with elicitor application, is a suitable technique to obtain large amounts of bioactive compounds. Haplophyllum virgatum is an Iranian endemic plant species. Sodium nitroprusside (SNP) is widely used as a nitric oxide (NO) donor in studies on plants to investigate the physiological roles of NO. Here, the physiological responses were investigated in cell suspension cultures of H. virgatum in the presence of different concentrations of SNP (0, 100, 150, and 200 µM) at various time points (0, 8, 12, 24, 48, 72, and 168 h). The transcript levels of two flavonoid biosynthetic enzymes, including chalcone synthase (CHS) and chalcone isomerase (CHI), and an important transcription factor (R2R3-MYB), were measured in the SNP-treated cells. The content of rutin (the main flavonoid in the Rutaceae family) was also evaluated. Nitric oxide significantly decreased the hydrogen peroxide and malondialdehyde contents by increasing the proline and enzymatic and non-enzymatic antioxidants in the treated cells. Meanwhile, NO significantly elicited flavonoid production, including rutin. These results highlight the effects of NO on flavonoid biosynthesis in H. virgatum suspension cells, probably through gene expression regulation in and upstream of the flavonoid biosynthetic pathway.