Methyl Jasmonate Induces Oxidative/Nitrosative Stress and the Accumulation of Antioxidant Metabolites in Phoenix Dactylifera L.

Abstract

Objectives The present study aimed at exploring the eliciting effects of increasing concentrations (50, 100, and 200 µM) of MeJA. We cultivated actively proliferating buds of Phoenix dactylifera L. cv. Barhee in a temporary immersion system and we monitored the bioactive compounds accumulation after 7 days of culture. Methods 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). Results Our results revealed that high MeJA concentrations induced an increase in the PAL, TAL and PPO activities. Several stress markers such as Hydrogen peroxide (H2O2), Nitric oxide (NO), Malondialdehyde (MDA), Superoxide dismutase (SOD), Catalase (CAT) and Guaiacol peroxidase (GPOD) were also found to rise. Beside, MeJA caused subsequent elevations in the amount of catechin, 4-Hydroxybenzoic acid, caffeic acid and p-Coumaric acid and antioxidant capacity with the lowest DPPH and ABTS IC50 values. Microscopic observations using fluorescence probes such as fluorescein diacetate (FDA) and acridine orange/ethidium bromide demonstrated that the supplementation of MeJA to culture media induced cells death in a dose dependent manner. Conclusion The findings suggest that in vitro cultures elicited by MeJA of Phoenix dactylifera L. have the capacity to produce secondary metabolites.