Wounding and UVB Light Synergistically Induce the Biosynthesis of Phenolic Compounds and Ascorbic Acid in Red Prickly Pears (Opuntia ficus-indica cv. Rojo Vigor)

Abstract

The present study evaluated the effects of ultraviolet B (UVB) radiation and wounding stress, applied alone or combined, on the biosynthesis of phenolic compounds and ascorbic acid in the peel and pulp of red prickly pear (Opuntia ficus-indica cv. Rojo Vigor). Whole and wounded-fruit samples were treated with UVB radiation (6.4 W·m−2) for 0 and 15 min, and stored for 24 h at 16 °C. Phytochemical analyses were performed separately in the peel and pulp. The highest phenolic accumulation occurred after storage of the whole tissue treated with UVB, where the main phenolic compounds accumulated in the peel and pulp were quercetin, sinapic acid, kaempferol, rosmarinic acid, and sinapoyl malate, showing increases of 709.8%, 570.2%, 442.8%, 439.9%, and 186.2%, respectively, as compared with the control before storage. Phenylalanine ammonia-lyase (PAL) activity was increased after storage of the whole and wounded tissue treated with UVB light, and this increase in PAL activity was associated to phenolic accumulation. On the other hand, l-galactono-γ-lactone dehydrogenase (GalLDH) activity and ascorbic acid biosynthesis was enhanced due to UVB radiation, and the effect was increased when UVB was applied in the wounded tissue showing 125.1% and 94.1% higher vitamin C content after storage when compared with the control. Respiration rate was increased due to wounding stress, whereas ethylene production was increased by wounding and UVB radiation in prickly pears. Results allowed the generation of a physiological model explaining the UVB and wound-induced accumulation of phenolic compounds and ascorbic acid in prickly pears, where wounding facilitates UVB to access the underlying tissue and enhances an apparent synergistic response.

Using High Hydrostatic Pressure Processing Come-Up Time as an Innovative Tool to Induce the Biosynthesis of Free and Bound Phenolics in Whole Carrots

“…Phenylalanine ammonia-lyase (PAL) activity was measured following the method reported by Ortega-Hernández et al (2019). Fresh carrot tissue (4 g) was homogenized with polyvinylpyrrolidone (0.4 g) in ice-cold 50 mM borate buffer (16 mL, pH 8.5) containing β-mercaptoethanol (5 mM) using a tissuemizer.…”

Altitudinal Variation of Metabolites, Mineral Elements and Antioxidant Activities of Rhodiola crenulata (Hook.f. & Thomson) H.Ohba

“…Flavonoids and phenylpropanoids possess the ability to resist a variety of adversity stresses such as UV radiation, low temperature, drought, or pathogen [ 21 , 22 , 23 , 24 , 25 , 26 ]. It has been shown that the amount and type of plant phenolics and ascorbic acid in the plant body would respond to a variety of adversities and play an important role in helping plants to withstand adversity stress [ 27 , 28 , 29 ]. Amino acid classes play an important physiological role in promoting plant growth and enhancing plant stress resistance in several ways [ 30 , 31 , 32 ].…”

Phosphoproteomics Reveals Regulation of Secondary Metabolites in Mahonia bealei Exposed to Ultraviolet-B Radiation

“…UV-B radiation can induce oxidative stress, which produces reactive oxygen species ( Ortega-Hernández et al, 2019 ) and then activates the plant ROS scavenging system ( Das and Roychoudhury, 2014 ). Our study results show that the contents of MDA and H 2 O 2 in M. bealei leaves were increased after exposure to UV-B radiation, and correspondingly, the activity of POD and SOD and T-AOC under the UV-B radiation was significantly improved ( p < 0.05), which was significant for the detoxification of oxidants produced by UV-B ( Czégény et al, 2016 ; Köhler et al, 2017 ).…”