“…Both abiotic and biotic elicitors have been extensively used for improving TIA production in C. roseus in vitro cultures since the beginning of the 1990s [ 105 , 107 , 108 , 109 ]. In fact, abiotic elicitors like metal ions and UV light, as well as biotic elicitors such as fungal preparations and yeast extracts, hydrolytic enzymes, chemicals (cyclodextrins (CDs) and signalling molecules like nitric oxide, jasmonic acid and derived compounds such as methyl jasmonate (MeJA) and acetylsalicylic acid were commonly used [ 73 , 84 , 85 , 110 , 111 , 112 ]. In this way, the treatment of C. roseus hairy root cultures with 0.1 mM sodium nitroprusside (NO donor) caused a significant increase of serpentine, catharanthine, ajmalicine, hörhammericine, lochnericine and tabersonine [ 78 ] ( Table 1 ).…”