Nitrogen deficiency stimulates biosynthesis of bioactive phenylethanoid glycosides in the medicinal plant Castilleja tenuiflora Benth

Castilleja tenuiflora Benth. (Orobanchaceae) in vitro cultures are alternative sources of phenylethanoid glycosides (PhGs), promising natural products for chronic diseases treatment because of their extensive range of biological activities. To increase the yields of these bioactive compounds, the identification of factors affecting their biosynthesis is required. Here, we show that N deficiency stimulates PhGs biosynthesis by increasing the activity of PAL. The contents of two PhGs, verbascoside and isoverbascoside, were enhanced under N deficiency compared with control conditions. The maximum PAL activity in shoots cultured under N deficiency was also increased. Furthermore, we found de novo anthocyanin synthesis under N deficiency suggesting an additional impact of this stress factor on flavonoid metabolism. N deficiency negatively affected the shoot growth (length, biomass, and total chlorophyll content) and multiplication rate, and inhibited the root formation of C. tenuiflora shoots. Our results demonstrate that N deficiency increases PhGs biosynthesis in C. tenuiflora.