Ménage à trois: light, terpenoids, and quality of plants.

Light spectral composition regulates terpenoid biosynthesis, abundances, and chemical diversity in both aboveground and belowground organs, thus impacting the nutritional and medicinal content, aroma, flavor, and color of plants. Red and blue (B) light regulation of terpenoid biosynthesis is mutually dependent, and a light spectrum >50% of red (R) tends to be detrimental to the biosynthesis of various terpenoids. The transcription factor elongated hypocotyl 5 (HY5) plays a central role in UV, R, and B light signaling regulating terpenoid biosynthesis. Beside HY5, MYB and trichome-specific transcription factors play a role in UV light signaling affecting terpenoids. In controlled environment agriculture (CEA), light is used to impact terpenoid production and improve plant quality. In this review we discuss various aspects of light as important regulators of terpenoid production in different plant organs. Spectral quality primarily modifies terpenoid profiles, while intensity and photoperiod influence abundances. The central regulator of light signal transduction elongated hypocotyl 5 (HY5) controls transcriptional regulation of terpenoids under UV, red (R), and blue (B) light. The larger the fraction of R and green (G) light, the more beneficial the effect on monoterpenoid and sesquiterpenoid biosynthesis, and such an effect may depend on the presence of B light. A large fraction of R light is mostly detrimental to tetraterpenoid production. We conclude that light is a promising tool to steer terpenoid production and potentially tailor the quality of plants. [ABSTRACT FROM AUTHOR]