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

Light quality in plant tissue culture: does it matter?

The primary issues regarding the lack of protocol reproducibility among laboratories are environmental factors. Light (quantity and particularly quality), is one of those main factors, and studies seldom present the spectral quality of the light sources used. With the advent of light-emitting diode (LED) technology, impressive progress has been made in environmental controls and morphogenetic responses, as directed by the light used in the culture shelves. A wide array of LED lights with different spectra are currently available and light is important in large-scale propagation, especially liquid bioreactor systems. LED technology continues to evolve rapidly and has created additional possibilities. This laboratory has dedicated extensive efforts to implement photoautotrophic propagation, and light is a key component of the system. This review presents relevant topics on the influence of light in various plant tissue culture-based techniques