Phenylpropanoids are naturally occurring compounds that exert beneficial pharmacological effects on human health. Phenylpropanoids can act as antioxidants and are involved in resistance to ultraviolet light and cancer; these compounds possess anti-inflammatory, antiviral, and antibacterial activity, and aid in wound healing. The expression of genes involved in phenylpropanoid biosynthesis, and consequent accumulation of phenylpropanoids in wheat sprout under conditions of stress, have not been extensively studied. This is the first study to examine the effects of light-emitting diodes (LED) on the expression of genes involved in phenylpropanoid biosynthesis and accumulation of phenylpropanoids in wheat sprouts. Our results, obtained using qRT-PCR and HPLC analyses, indicate that white light (380 nm) was the optimal wavelength for epicatechin biosynthesis in wheat sprouts. Compared with the effects of white light, blue light (470 nm) enhanced the accumulation of gallic acid and quercetin, but decreased the levels of p-coumaric acid and epicatechin; red light (660 nm) increased the accumulation of ferulic acid at 8 day and p-coumaric acid at 12 day. Compared gene expression with phenylpropanoid content showed that TaPAL3, TaPAL4, and TaDFR maybe important genes in phenylpropanoid biosynthesis in wheat sprout. This study provides insights into the effects of led lights on phenylpropanoid production in wheat sprouts. This knowledge will help improve secondary metabolite production in wheat sprouts.

The effect of salinity (NaCl treatment) on the nutritive value of wheat sprouts was investigated by analyzing the expression of phenylpropanoid biosynthetic pathway genes and the levels of phenylpropanoid compounds. Treatment with various concentrations of NaCl (50, 100, and 200 mM) resulted in increased epicatechin levels but decreased accumulation of catechin hydrate, benzoic acid, and quercetin compounds in the sprouts compared with the control (0 mM). The trans-cinnamic acid, 4-hydroxybenzoic acid, ferulic acid, epicatechin, and total phenylpropanoid level in wheat sprout was the highest at 50 mM of NaCl treatment. Six-day-old wheat plantlets exposed to 50 mM NaCl for 6, 12, 24, 48, and 72 h, showed that the total phenylpropanoids accumulation was the highest at 48 h after the treatment and most of the treatments showed higher phenylpropanoid content than the control at the same time points. Although the shoot and root length and the fresh weight of wheat sprouts decreased with NaCl treatment, these results suggest that treatment of 50 mM NaCl improves the nutritional quality of wheat sprouts, due to increased phenylpropanoid concentrations.

Phenylpropanoids and flavonoids belong to a large group of secondary metabolites, and are considered to have antioxidant activity, which protects the cells against biotic and abiotic stresses. However, the accumulation of phenylpropanoids and flavonoids in bitter melon has rarely been studied. Here, we identify ten putative phenylpropanoid and flavonoid biosynthetic genes in bitter melon. Most genes were highly expressed in leaves and/or flowers. HPLC analysis showed that rutin and epicatechin were the most abundant compounds in bitter melon. Rutin content was the highest in leaves, whereas epicatechin was highly accumulated in flowers and fruits. The accumulation patterns of trans-cinnamic acid, p-coumaric acid, ferulic acid, kaempferol, and rutin coincide with the expression patterns of McPAL, McC4H, McCOMT, McFLS, and Mc3GT, respectively, suggesting that these genes play important roles in phenylpropanoid and flavonoid biosynthesis in bitter melon. In addition, we also investigated the optimum light conditions for enhancing phenylpropanoid and flavonoid biosynthesis and found that blue light was the most effective wavelength for enhanced accumulation of phenylpropanoids and flavonoids in bitter melon.

Salinity stress affects plants by reducing the water potential and causing ion imbalance or disturbances in ion homeostasis and toxicity. Salinity stress frequently causes both osmotic and ionic stress in plants, resulting in the increase or decrease of certain secondary metabolites in plants. In this study, the effect of NaCl treatment on the nutritional quality of tartary buckwheat plants was studied by conducting an HPLC analysis of phenylpropanoid and anthocyanin content. It was observed that there was no significant change of color in tartary buckwheat during salt treatment. The accumulation of most phenylpropanoid compounds increased slightly in response to the NaCl concentration. The total phenylpropanoid content in tartary buckwheat was the highest at 100 mM NaCl treatment. Seven-day-old wheat plantlets treated with 100 mM NaCl for 2, 4, 6, and 8 days showed the highest accumulation of total phenylpropanoids at day 8 after treatment, while the content of most phenylpropanoids was higher than that in the control during this period. Although the development of tartary buckwheat slightly decreased with NaCl treatment and the accumulation of anthocyanin compounds did not change in plants with a diffident NaCl concentration and time treatment, the results suggest that the salinity treatment of tartary buckwheat causes antioxidant activity improvement by inducing an accumulation of flavonoid and phenolic compounds. However, since the anthocyanin content did not increase, the antioxidant effect of the treatment is not expected to be significant.