# Impact of Environmental Factors on Stilbene Biosynthesis
## 3 Impact of Environmental Factors on the Biosynthesis of Stilbenes
### Elicitation
Induction of resveratrol by treating peanut cell suspension cultures with YE was reported by [PERSON] and co-workers [320]. A single elicitation treatment with sodium acetate of peanut hairy root cultures resulted in a 60-fold induction and secretion of _trans_-resveratrol into the medium after 24 h [321]. Several studies have been conducted with various elicitors to enhance stilbene production in both pre- and post-harvest grape berries. In 2015, [PERSON] and colleagues [322] investigated for the first time the effect of pre-harvest UV elicitation in grapevines. Twenty-four hours after the UV-C pre-harvest treatment, they observed a 22 to 46-folds increasein _trans_-resveratrol content in table grapes cv. Red Globe. They subsequently reported that pre-harvest UV-C treatment repeated for 3 consecutive days resulted in an 86-fold increase in stilbenoid content (_trans_-resveratrol, _trans_-piceatanmol, isorhapontigenin, _cis_- and _trans_-piceid, _e_- and _o_-v-vinferin) in table grapes cv. Crimson seedless [323]. As previously mentioned (Section 3.1), a vast literature describes the impact of UV elicitation on stilbene accumulation in post-harvest grapes [94; 324]. In 2019, [PERSON] and co-workers [325] recently investigated the impact of post-harvest ozone elicitation on the biosynthesis of stilbenes in Moscato binoergues. They found that short-term treatment with high ozone doses (60 \(\upmu\)L/L; 48 h exposure) not only prevented the loss of stilbenes during the dehydration process but also induced the accumulation of _trans_-resveratrol and _trans_-piceatanmol. Surprisingly, long-term and continuous ozone treatment did not induce _trans_-resveratrol production, but it did not negatively affect the stilbene content in winegrapes. Consequently, the use of ozone could have important applications in winemaking to produce wines with high added value considering both the possible reduction of SO2 addition and, under certain conditions, increased contents of stilbenes [325]. Ultrasonication is mechanical stress that can affect stilbene biosynthesis, dramatically increasing resveratrol levels in peanut kernels, as well as in grape skin and leaves. Recent reviews [20; 326] thoroughly covered this topic, reporting an increase in _trans_-resveratrol, _trans_-piceid in peanuts [201; 327], and an increase of resveratrol coupled with the up-regulation of the resveratrol synthase (RS) gene in grape skins and leaves [328] treated with ultrasound. It was also reported that short-term exposure to low power ultrasonication is more effective in eliciting resveratrol accumulation. More recently, [PERSON] and co-workers [329] obtained similar results in peanut sprouts, which responded to ultrasound treatment with an increase in _trans_-resveratrol, accompanied by a slight increase in total sugars and a remarkable decrease in crude fat and peanut allergenic proteins. Despite these promising results, the use of ultrasonication as a physical elicitor to increase the biotechnological stilbene production in vitro has been poorly investigated. The first published study on this topic dates to 2012 when [PERSON] and collaborators [219] reported the accumulation of _trans_-resveratrol, _trans_-piceid, _trans_-_e_-vinferin, _trans_-_b_-v-vinferin, and _cis_-v-vinferin in grapevine cv. [PERSON] cell suspensions in response to low-energy ultrasounds.