Red : far‐red light ratio and UV‐B radiation: their effects on leaf phenolics and growth of silver birch seedlings

Abstract

The natural variation in quantity and quality of light modifies plant morphology, growth rate and concentration of biochemicals. The aim of two growth-room experiments was to study the combined effects of red (R) and far-red (FR) light and ultraviolet-B (UV-B) radiation on the concentrations of leaf phenolics and growth and morphology of silver birch ( Betula pendula Roth) seedlings. Analysis by high-performance liquid chromatography showed that the leaves exposed to supplemental FR relative to R contained higher concentrations of total chlorogenic acids and a cinnamic acid derivative than the leaves treated with supplemental R relative to FR. In contrast, concentration of a flavonoid, quercetin 3-galactoside, was higher in the R + + + + UV-B leaves than in the FR + + + + UV-B leaves. The UV-B induced production of kaempferols, chlorogenic acids and most quercetins were not modified by the R : FR ratio. Growth measurements showed that the leaf petioles and stems of FR seedlings were clearly longer than those of R seedlings, but leaf area was reduced by UV-B radiation. Results of these experiments show that exposure of silver birch seedlings to supplemental FR compared to R leads to fast elongation growth and accumulation of phenolic acids in the leaves.

The influence of light quality on phenolic acid and biflavonoid production in Anacardium othonianum Rizz. seedlings grown in vitro

“…A recent study of Cyclopia subternata callus cultures cultivated under various light conditions showed that blue light resulted in the highest levels of the flavonoid hesperidin and the isoflavones 7-O-β-glucosides (Kokotkiewicz et al, 2014). The enhanced concentration of the flavonoid amentoflavone under blue light found in the present study is in agreement with several researchers (Awad et al, 2001;Tegelberg et al, 2004), indicating that blue light has a beneficial effect on the accumulation of flavonoids in in vitro cultures.…”

“…In this study, their responses to light were differed. This finding was also observed in Betula pendula seedlings by Tegelberg et al (2004). An alternative biosynthetic pathway for the formation of gallic and 3,4-dihydroxibenzoic acid involves the precursor of shikimic acid, 3-dehydroshikimic acid.…”

“…Molecular studies have revealed that CHS expression levels vary according to the type of incident light used for plants. Thus, flavonoid content may also vary in this manner (Mustafa and Verpoorte, 2007;Tegelberg et al, 2004;Wade et al, 2001).…”

Light emitting diodes increase phenolics of buckwheat (Fagopyrum esculentum) sprouts

“…Kefeli and Kalevitch (2002) stated that the precursors of plant growth regulators are strongly connected with the primary product of photosynthesis and there is some evidence that IAA affects the formation of phenolic compounds in plants. In addition, cinnamic acid has physiological significance in buckwheat (Kefeli & Kalevitch 2002), which is necessary for flavonoids synthesis in plants (Tegelberg et al 2004). But in this study, only the major polyphenols were determined and their ability to influence auxin levels in buckwheat sprouts is not known yet although there are also some reports that flavonoids may regulate the polar transport of auxin (Brown et al 2001, Tegelberg et al 2004.…”

“…According to Tegelberg et al (2004), the concentrations of flavonoids may be varied with the qualitative changes in incident light. Solar radiation and day length conditions increased the accumulation of rutin in buckwheat (Fagopyrum esculentum) (Ohara et al 1989, Ohsawa & Tsutsumi 1995.…”