Light quality affects in vitro growth and essential oil profile in Lippia alba (Verbenaceae)

This study evaluated the influence of light quality on growth and essential oil production in three chemotypes of Lippia alba (BGEN-01, BGEN-02, and BGEN-42) grown in vitro. These chemotypes differed both in ploidy and in the predominant essential oil produced. The treatments were fluorescent lamps, white light-emitting diode (LED) bulbs, and blue/red LEDs, all with the same irradiance. After 40 d of culture on hormone-free MS medium, analysis of the essential oil profile and quantitative analysis of growth parameters—plant height, fresh, and dry weight, total chlorophyll, and total carotenoids—were performed. Light quality significantly influenced the in vitro growth of L. alba. Compared to the control, blue/red LEDs induced greater fresh and dry weight in BGEN-01 and BGEN-02 and less in BGEN-42. Photosynthetic pigment levels were higher in plants grown under blue/red LEDs for all chemotypes. Multivariate analysis allowed the identification of different patterns of essential oil production among the treatments. The composition of the volatile compounds varied with light quality and chemotype, with the differences due mainly to the amounts of eucalyptol and linalool. The knowledge of this relationship between light quality and essential oil profile provides a basis for further studies at the genetic level that may elucidate how this regulation works, thereby enabling tailored production of compounds of interest.