2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid and methyl-jasmonate

The present study aimed to explore the eliciting effects of increasing concentrations (50, 100, and 200 µM) of methyl jasmonate (MeJA). We cultivated actively proliferating buds of Phoenix dactylifera L. cv. Barhee in a temporary immersion system and we monitored the bioactive compound accumulation after 7 days of culture.. Total phenolic (TPC) and flavonoid (TFC) contents were determined by high-performance liquid chromatography (HPLC), Fourier-transform infrared (FTIR), and radical scavenging activity using DPPH and ABTS assays. We also explored the activity of phenylpropanoid pathway enzymes, namely phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL) and polyphenol oxidase (PPO).. Our results revealed that MeJA treatment induced oxidative stress, and at the same time increased the activity of related defense enzymes in a dose-dependent manner. Exogenous application of MeJA at 200 µM increased ROS (two fold), hydrogen peroxide (3.7 fold), nitric oxide (14 fold), MDA (6.3 fold), superoxide dismutase (5.9 fold), catalase (4.4 fold) and guaiacol peroxidase (3.87 fold). Furthermore, the results demonstrated that 200 µM MeJA treatment enhanced the activities of PAL (3.65 fold), TAL (4.35 fold), PPO (threefold) and increased TPC (twofold) and TFC (1.75 fold) contents in buds cultures higher than the control. HPLC analysis showed that buds cultures exposed to 200 µM MeJA accumulated maximum amount of catechin (11 fold), 4-hydroxybenzoic acid (1.48 fold), caffeic acid (2.5 fold) and p-coumaric acid (1.76 fold) and demonstrate antioxidant capacity with the lowest DPPH (114.5 µg ml. The results of this study has revealed, for the first time, that MeJA offers a promising potential for the production of phenolic compound in Phoenix dactylifera L. buds.

Topics: Acetates; Antioxidants; Cyclopentanes; Nitrosative Stress; Oxidative Stress; Oxylipins; Phenols; Phenylalanine Ammonia-Lyase; Phoeniceae

Stilbenoids are polyphenolic phytoalexins that exhibit potential health applications in humans. Hairy root cultures of muscadine grape (Vitis rotundifolia Michx.) were used to study the biochemical and molecular regulation of stilbenoid biosynthesis upon treatment with 100 μM methyl jasmonate (MeJA) or 10 mM hydrogen peroxide (H2O2) over a 96-h period. Resveratrol, piceid, and ε-viniferin were identified in higher concentrations in the tissue whereas resveratrol was the most abundant stilbenoid in the medium under either treatment. An earlier increase in resveratrol accumulation was observed for the MeJA-treated group showing a maximum at 12 h in the tissue and 18 h in the medium. Furthermore, the antioxidant capacity of extracts from the tissue and medium was determined by the 2,2'-azinobis[3-ethylbenzthiazoline sulfonic acid] (ABTS) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays showing correlation with the stilbenoid content. Fourteen candidate reference genes for qPCR were tested under the described experimental conditions and resulted in the selection of 5 reference genes. Quantitative analyses of transcripts for phenylalanine ammonia-lyase (PAL), resveratrol synthase (RS), and two stilbene synthases (STS and STS2) showed the highest RNA level induction at 3 h for both treatments with a higher induction for the MeJA treatment. In contrast, the flavonoid-related chalcone synthase (CHS) transcripts showed induction and a decrease in expression for MeJA and H2O2 treatments, respectively. The observed responses could be related to an oxidative burst triggered by the exposure to abiotic stressor compounds with signaling function such as MeJA and H2O2 which have been previously related to the synthesis of secondary metabolites.

Topics: Acetates; Antioxidants; Benzothiazoles; Biphenyl Compounds; Culture Media; Cyclopentanes; Genes, Plant; Hydrogen Peroxide; Oxylipins; Picrates; Plant Roots; RNA, Plant; Stilbenes; Sulfonic Acids; Vitis