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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.

The present study is a part of a program designed at improving the date palm, Phoenix dactylifera L. cv. Barhee, through induced somaclonal variation. In this work, caulogenic cultures were subcultured on MS media supplemented with 0, 1, 5, 10, 20 and 40 mg L− 1 2,4-D in order to induce genetic and epigenetic variations. The highest doses of 2,4-D were found to induce severe negative effects on in vitro cultures, although some tissues were able to survive and to produce calli with high morphogenetic capacities. Our analysis showed some significant effect of 2,4-D on several physiological parameters. Indeed, chlorophyll and growth rates were found to drastically decrease while proline content increased from 535 nmol g− 1 to 2973 nmol g− 1 FW when 40 mg L− 1 2,4-D were used. In vitro cultures showed several signs of oxidative stress, such as high levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA); likewise, the specific activity of several antioxidant enzyme was found to increase. Plant regeneration from in vitro cultures treated with 2,4-D was obtained after subculturing explants onto PGR-free media. The ISSR analysis of 2,4-D-treated material showed that this plant growth regulator (PGR) induced measurable genetic variations. The global DNA methylation rates (GMR) as estimated through the HPLC analysis of nucleosides also confirmed the presence of epigenetic changes caused by 2,4-D as GMRs increased from 13.8–18.93%.

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. MethodsTotal phenolic (TPC) and avonoid (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). ResultsOur results revealed that high MeJA concentrations induced an increase in the PAL, TAL and PPO activities. Several stress markers such as Hydrogen peroxide (H 2 O 2 ), 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 uorescence probes such as uorescein diacetate (FDA) and acridine orange/ethidium bromide demonstrated that the supplementation of MeJA to culture media induced cells death in a dose dependent manner. ConclusionThe ndings suggest that in vitro cultures elicited by MeJA of Phoenix dactylifera L. have the capacity to produce secondary metabolites.

The present study is a part of a program designed at improving the date palm, Phoenix dactylifera L. cv. Barhee, through induced somaclonal variation. In this work, caulogenic cultures were subcultured on MS media supplemented with 0, 1, 5, 10, 20 and 40 mg L − 1 2,4-D in order to induce genetic and epigenetic variations. The highest doses of 2,4-D were found to induce severe negative effects on in vitro cultures, although some tissues were able to survive and to produce calli with high morphogenetic capacities. Our analysis showed some signi cant effect of 2,4-D on several physiological parameters. Indeed, chlorophyll and growth rates were found to drastically decrease while proline content increased from 535 nmol g − 1 to 2973 nmol g − 1 FW when 40 mg L − 1 2,4-D were used. In vitro cultures showed several signs of oxidative stress, such as high levels of hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA); likewise, the speci c activity of several antioxidant enzyme was found to increase. Plant regeneration from in vitro cultures treated with 2,4-D was obtained after subculturing explants onto PGR-free media. The ISSR analysis of 2,4-D-treated material showed that this plant growth regulator (PGR) induced measurable genetic variations. The global DNA methylation rates (GMR) as estimated through the HPLC analysis of nucleosides also con rmed the presence of epigenetic changes caused by 2,4-D as GMRs increased from 13.8-18.93%. Key MessageResults demonstrate that the 2,4-D can affect physiological and molecular parameters of vitrocultures when used at high concentrations without hampering their morphogenetic capacities. It was found to be e cient at inducing genetic and epigenetic variations.