Blue LED light enhances growth, phytochemical contents, and antioxidant enzyme activities of Rehmannia glutinosa cultured in vitro

Abstract

The objective of the current study is to determine the effect of light quality on enhancement of growth, phytochemicals, antioxidant potential, and antioxidant enzyme activities at in vitro cultures of Rehmannia glutinosa Libosch. In vitro-grown shoot tip explants were cultured on the plant growth regulator (PGR)-free Murashige and Skoog (MS) medium and cultured under a conventional cool white fluorescent light (control), blue light emitting diode (LED) light or red LED light. After four weeks, the growth traits along with total phenol content, total flavonoid content, free radical scavenging activities, and antioxidant enzyme activities were measured. Interestingly, the blue or red LED treatments showed a significant increase in growth parameters compared with the cool white florescent light. In addition, the LED treatments increased the total phenol and flavonoid levels in leaf and root extracts. Furthermore, data on the total antioxidant capacity, reducing power potential, and DPPH radical scavenging capacity also revealed the enhancement of antioxidant capacity under both blue and red LED treatments. Especially, the blue LED treatment significantly increased the antioxidant enzyme activities in both the leaf and root, followed by the red LED treatment. Modulation in the spectral quality particularly by the blue LED induced the antioxidant defense line and was directly correlated with the enhancement of phytochemicals. Therefore, the incorporation of blue or red LED light sources during in vitro propagation of R. glutinosa can be a beneficial way to increase the medicinal values of the plant.Additional key words: antioxidant potential, light emitting diodes, metabolite enhancement, secondary metabolites Hort.

Effects of Light Quality on Morphology, Enzyme Activities, and Bioactive Compound Contents in Anoectochilus roxburghii

“…Galdiano et al (2012) showed that red light strongly promoted chlorophyll b synthesis in Cattleya loddigesii Lindl.. Similar results were also reported for R. glutinosa and Triticum aestivum L. (Dong et al, 2014; Manivannan et al, 2015). However, Kobayashi et al (2013) reported that the chlorophyll content in lettuce leaves was higher under blue light than under red light.…”

Effects of Light Quality on The Quality Formation of Tomato Fruits

“…The increase in contents of total phenol and flavonoid by the LED treatments has a strong positive correlation with the enhancement of antioxidant capacity [30]. Red and blue compound light affects antioxidant capacity and radical scavenging potential by affecting the contents of polyphenol and flavonoid.…”

Effects of Light Quality on Growth and Phytonutrient Accumulation of Herbs under Controlled Environments

“…Since light quality does affect the biosynthesis of phytonutrients, it is possible to improve antioxidant activities of herbs by altering the light spectrum, thus providing more natural antioxidants in our daily food. For instance, monochromatic red and blue LED light both enhanced the antioxidant capacities, total phenolics, and flavonoids in Chinese foxglove compared with white FL, and blue light was more efficient than red light [53]. Similar to the effects of light quality on growth parameters and some secondary metabolites, the enhancement of combined red and blue light was more efficient than monochromatic red or blue light only.…”

“…Monochromatic red or blue light treatments significantly increased the concentrations of total phenolic compounds, flavonoids, and anthocyanins in Chinese foxglove (Rehmannia glutinosa) and perilla plants compared with white light, and blue light was more efficient than red light [53,58]. However, the amount of rosmarinic acid-the major component of phenolic compounds in sweet basil-under continuous red and white light was double that under blue light, all at 100 µmol m −2 s −1 PPF for 14 days, whereas chicoric acid content, the second major component, was highest under white light, followed by blue and red light [59,60].…”

“…With increasing consumption of herbs, growers are adopting CEA systems for herb production to provide sufficient quantity and quality of natural products. As LEDs are increasingly being used in controlled environment horticulture, the effects of light quality (spectrum distribution of light sources) on phytonutrient accumulation have been increasingly investigated [16,36,49,53], which will be discussed in the following sections.…”