# Impact of Environmental Factors on Stilbene Biosynthesis
## 3 Impact of Environmental Factors on the Biosynthesis of Stilbenes
### Elicitation  
Plant cell and organ cultures obtained from stilbene-producing plants represent a reliable model system, both for basic research on plant defense mechanisms and for the biotechnological stilbene production, that can be induced and/or enhanced by a wide range of elicitors. The term elicitor, which was originally referred to as molecules capable of inducing the biosynthesis of phytoalexins in plants, is currently used to designate any physical and chemical factors that can trigger any kind of defense response in plants [301]. Elicitors can be classified, according to their nature, as \"abiotic elicitors\" or \"biotic elicitors\" and, according to their origin, as \"exogenous elicitors\" or \"endogenous elicitors\" [301; 302]. Elicitation has mainly been investigated as a tool to enhance the in vitro production of stilbenes [40; 219; 233; 303; 304]. However, in recent years increasing attention has been paid to elicitation in both pre- and post-harvest in vivo models, as a strategy to induce the natural plant defenses against pathogens and to improve the health properties of plant foods [188; 189; 305; 306; 307]. Methyl jasmonate (MeJa) has been shown to be the most effective elicitor for promoting stilbene production in grapevine cell cultures [219; 227; 233; 234; 303; 308; 309]. However, stilbenes are mainly accumulated intracellularly and only a small fraction of them is released into the culture medium by MeJa-treated grapevine cells. Complexation with cyclodext (CDs) promotes the release of stilbenes into the medium [304; 310]. CDs are cyclic oligosaccharides that have been reported to activate the expression of stilbene biosynthetic genes through the induction of several transcription factors in grapevine [311]. Dimethyl-\(\beta\)-CDs have been shown to act as elicitors capable of stimulating the biosynthesis of stilbenes, as well as promoting their release in the medium and increasing their stability [304; 308]. The efficacy of the combined use of MeJa and dimethyl-\(\beta\)-CDs in enhancing the biosynthesis and the extracellular secretion of stilbenes in grapevine cell cultures has been demonstrated by extensive literature [228; 304; 311; 312; 313; 314]. It has been recently reported that the co-treatment with MeJa and stevioside (aiterpene glycoside extracted from leaves of _Stevia rebaudiana_ [PERSON]), elicits the production and extracellular secretion of resveratrol and viniferins in cell cultures of _V. labruscana_ cv. [PERSON] [304]. CDs have been widely exploited to enhance the production of stilbene compounds in hairy root cultures of _A. hypogaea_. Co-treatment of peanut hairy roots with CDs and MeJa induced the production and secretion in the culture medium of _trans_-resveratrol, piceatannol, _trans_-arachidin-1, and _trans_-arachidin-3 [242]. In 2019, [PERSON] and colleagues [315] reported that the elicitation of _A. hypogaea_ hairy roots with the herbicide paraquat (1,1\({}^{\prime}\)-dimethyl-4,4\({}^{\prime}\)-bipyridinium dichloride), followed by the combination of MeJa and CDs, resulted in increased amounts of stilbene compounds like _trans_-resveratrol, _trans_-arachidin-1, and _trans_-arachidin-3. Physical elicitors have also been widely exploited for the induction of stilbenes production in peanut, as discussed by [PERSON] et al. [299] and [PERSON] et al. [316]. The elicitation of white mulberry (_Morus alba_) callus cultures with 2-hydroxypropyl-\(\beta\)-CD has been shown to improve resveratrol and oxyresveratrol production [317]. It has also been shown that the treatment of cell suspension cultures of _M. alba_ with MeJa and yeast extract (YE) increases the production of oxyresveratrol and resveratrol [318]. A recent investigation has demonstrated that root cultures of _M. alba_ co-treated with MeJa and YE produce relatively high levels of resveratrol, oxyresveratrol, and mulberroside A [319]. In peanut, different chemical elicitors proved to be effective in inducing the biosynthesis of stilbene phytoalexins.