# Impact of Environmental Factors on Stilbene Biosynthesis
## 3 Impact of Environmental Factors on the Biosynthesis of Stilbenes
### Light  
Light is vital for plants, representing the main energy source for these phototrophic organisms. Light plays a pivotal role in plant growth and development, but it also affects secondary metabolism [270; 20]. Extensive literature shows the relationship between light and biosynthesis of polyphenol compounds such as anthocyanins and flavonoids [271; 272]. However, only a limited number of studies are available on the light-dependent regulation of the stilbene biosynthetic pathway.  
Advancements in technology have recently brought light-emitting diodes (LEDs) to the scene of botanical research, allowing for the use of specific wavelengths at high irradiance levels, with realistic results on the study of plant physiological responses to them [273]. Although there is still scarce information about stilbene biosynthesis in response to LED lighting, several studies observed an increase in stilbene biosynthesis, as well as in the expression of stilbene biosynthetic genes, in grapevine exposed to specific wavelengths.  
The influence of red LED light (625 nm) and methyl jasmonate (MeJa) on the production of phenylpropanoids in _V. vinifera_ cv. Barbera cell suspension cultures were investigated by [PERSON] and co-workers [211]. The combined treatment with red light and MeJa increased the biosynthesis of both anthocyanins and stilbenes, while also promoting the release of catechins into the culture medium. The treatment with red light alone produced a 50% increase in stilbene content in grapevine cells, accompanied by an average decrease in anthocyanin and catechin content of 10% and 18%, respectively. These results suggest a diversion of the phenylpropanoid pathway towards the production of stilbenes under red light [211].  
A series of experiments on berries of _V. labruscana_ Bailey cvs. Campbell Early and Kyoho irradiated with fluorescent white light or purple (380 nm), blue (440 nm), and red (660 nm) LED lights showed that red and blue light induces the upregulation of several _STS_ genes and the accumulation of _trans-_ and _cis-_resveratrol_, _trans-_ and _cis_-piceid, and piceatannol both in grape berry skin [212], and in detached leaves [213].  
In 2015, [PERSON] and colleagues [214] observed an inhibitory effect of light on _trans_-resveratrol production and an enhancement of _trans_-piceid biosynthesis in cell suspension cultures of _V. vinifera_ cv. Negramaro. Moreover, in 2018, [PERSON] and collaborators [215] reported that high-level white light irradiation (10,000 lux) inhibits the biosynthesis of _trans_-piceid and _trans_-resveratrol in cell suspension cultures of _V. vinifera_ cv. Shahai.  
Interesting differences in the impact of light on constitutive and Melja-induced stilbene biosynthesis emerged from the comparison of cell lines of _V. vinifera_ cv. Malvasia and _V. rupestris_ Du Lot [40]. In both species, the constitutive stilbene content was higher under light conditions, although _V. vinifera_ mainly accumulated picedi, while _V. rupestris_ accumulated _trans_-resveratrol, _trans_-_s-vriniferin, and _trans_-_e-vriniferin. Furthermore, _V. vinifera_ cells responded to MeJa elicitation with a significant increase in stilbene production under both light and dark conditions, while _V. rupestris_ cells were responsive to elicitation exclusively under dark conditions [40].  
Research has only recently begun to investigate the relationship between light and stilbene biosynthesis in species other than grapevine. A study on _A. hypogaea_ sprouts treated with UV-C and white LED light showed a significant response to white light in stilbene accumulation by the upregulation of genes and enzymes involved in their biosynthetic pathway, although less prominent than that observed in response to UV-C [216].