Effect of Light of Different Spectral Compositions on Pro/Antioxidant Status, Content of Some Pigments and Secondary Metabolites and Expression of Related Genes in Scots Pine

Abstract

The aim of this study was to investigate the effect of light quality (white fluorescent light, WFL, containing UV components), red light (RL, 660 nm), blue light (BL, 450 nm), and white LED light (WL, 450 + 580 nm) on the components of the cellular antioxidant system in Pinus sylvestris L. in needles, roots, and hypocotyls, focusing on the accumulation of key secondary metabolites and the expression of related genes. The qualitative and quantitative composition of carotenoids; the content of the main photosynthetic pigments, phenolic compounds, flavonoids (catechins, proanthocyanidins, anthocyanins), ascorbate, and glutathione; the activity of the main antioxidant enzymes; the content of hydrogen peroxide; and the intensity of lipid peroxidation (MDA and 4-HNE contents) were determined. RL resulted in an increase in the content of hydrogen peroxide and 4-HNE, as well as the total fraction of flavonoids in the needles. It also enhanced the expression of several PR (pathogen-related) genes compared to BL and WL. WFL increased the content of phenols, including flavonoids, and enhanced the overall activity of low-molecular antioxidants in needles and hypocotyls. BL increased the content of ascorbate and glutathione, including reduced glutathione, in the needles and simultaneously decreased the activity of peroxidases. Thus, by modifying the light quality, it is possible to regulate the accumulation of secondary metabolites in pine roots and needles, thereby influencing their resistance to various biotic and abiotic stressors.

Influence of Additional White, Red and Far-Red Light on Growth, Secondary Metabolites and Expression of Hormone Signaling Genes in Scots Pine under Sunlight

“…Light quality also affects the formation of secondary metabolites, including in conifers [42]. The activation of the biosynthesis of several secondary metabolites by light under different spectral compositions has been observed in higher plants [22]. Most often, this occurs because photoreceptors can bind to the promoter regions of the genes for light-dependent transcription factors, such as HY5 and PIFs, which, in turn, can change the expression of genes encoding key enzymes involved in the biosynthesis of phenylpropanoids, flavonoids and terpenoids [45].…”

“…In previous works, we found that narrowband RL had a specific effect on Scots pine seedlings and plantlets [1,2,22]. We hypothesized that the RL activation of various PHY and auxin signaling components stimulates an increase in the number of xylem cells [2].…”

“…We hypothesized that the RL activation of various PHY and auxin signaling components stimulates an increase in the number of xylem cells [2]. RL can regulate stem growth via the effects of phytohormones and secondary metabolites [1,22]. However, the influence of light quality on physiological responses and associated gene expression in Scots pine requires further study.…”

Photosynthesis under Environmental Fluctuations: A Challenge for Plants, a Challenge for Researchers

“…The combined response to light and heat is the subject of the study proposed by Krevlaski et al: using phytochrome mutants of the model angiosperm Arabidopsis thaliana, the authors offer evidence that a low red/far-red ratio is favourable for the prevention of PSII photoinhibition under moderate short-term thermal stress [11]. The stress-protective effect of red light is confirmed by Pashkovskiy et al, who report their experiment on the consequences of light quality manipulation on the secondary metabolism in Pinus sylvestris plantlets, observing effects on the quantity of antioxidants and carotenoids in needles [12].…”