Hazelnut is one of the most important nut plants recently suggested as a sustainable source for paclitaxel. In the present study, the effect of the concentration and combination of PGRs, different basal medium and ultrasonic waves on callus induction and growth, physiological characteristics, and taxol and baccatin III production in hazelnut callus cultures were investigated. The results indicated that combining 2,4-D (2 mg/L) and Kin (0.2 mg/L) with the sonication of explants for 1 min provides an optimized condition for callus induction and growth. Hazelnut explants exhibited different callus production and biochemical and metabolic characteristics depending on the basal medium type, ultrasound treatment, and inclusion of ascorbic acid in the medium. So that, the highest percentage of callogenesis (100%) observed in ½ MS + 1 min US, ½ MS + 150 mg/L AA, B5 + 1 min US and B5 + 150 mg/L AA, and also ½ MS salt + Nitsch vitamins + 150 mg/L AA. Furthermore, the highest callus growth (7.86 g FW) was obtained from ½ MS + 1 min US. The highest amount of baccatin III production (147.98 and 147.85 mg/L) was obtained from the WPM and MS basal media; the highest taxol production (44.89 mg/L) was observed in the WPM basal medium. The cultures in the MS, WPM, and MS salts + Nitsch vitamins media, had the highest H₂O₂ and MDA content, antioxidant enzymes activity, and phenolic compounds. In conclusion, culture media nutrient composition and concentration not only affect the cell growth and physiological status of the cultures but also improve secondary metabolites production and accumulation.

Melia azedarach L. is a valuable source of antioxidants and secondary metabolites. This study is a first extensive report about the effect of different serialization protocols and plant growth regulators (PGRs) on explant disinfection efficiency, callus induction and secondary metabolites production and accumulation in callus cultures of M. azedarach L. In this regard, the effect of plant growth regulators on callus induction and secondary metabolites production were examined. In addition, different sterilization agents were evaluated for disinfection of chinaberry leaf explants. The results showed that the lowest percentage of explant contamination and browning with the highest percentage of callus induction and callus growth obtained with explants pretreated with benomyl (2 g/L) for 2 h and sterilized with 7% H₂O₂ for 10 min and NaOCl 2% (without pH adjustment) for 12 min. Although adjusting the pH of NaOCl to pH = 7 and 10 significantly reduced the microbial contamination and increased the percentage of contamination-free cultures of M. azedarach L., adversely influenced the explant viability and callus induction and growth. The highest percentage of callus induction obtained on the MS medium containing 3 mg/L NAA/2,4-D and 1 or 3 mg/L Kin/BAP, and the highest callus yield (1804.833 mg/explant) belonged to the MS medium supplemented with 5 mg/L 2,4-D and 5 mg/L Kin. The callus cultures grown on the MS medium supplemented with 3 mg/L NAA and 1 mg/L Kin produced the highest amount of Quercetin (2.06 mg/g fresh weight), Rutin (5.56 mg/g fresh weight) and Kaempferol (1.84 mg/g fresh weight).

Cationic polyamidoamine (PAMAM) dendrimers are highly branched nanoparticles with unique molecular properties, which make them promising nanocarriers for gene delivery into cells. This research evaluated the ability of hyperbranched PAMAM (hPAMAM)-G2 with a diethylenetriamine core to interact with DNA, its protection from ultrasonic damage, and delivery to alfalfa cells. Additionally, the effects of ultrasound on the efficacy of hPAMAM-G2 for the delivery and expression of the gus A gene in the alfalfa cells were investigated. The electrophoresis retardation of plasmid DNA occurred at an N/P ratio (where N is the number of hPAMAM nitrogen atoms and P is the number of DNA phosphorus atoms) of 3 and above, and hPAMAM-G2 dendrimers completely immobilized the DNA at an N/P ratio of 4. The analysis of the DNA dissociated from the dendriplexes revealed a partial protection of the DNA from ultrasound damage at N/P ratios lower than 2, and with increasing N/P ratios, the DNA was better protected. Sonication of the alfalfa cells in the presence of ssDNA-FITC-hPAMAM increased the ssDNA delivery efficiency to 36%, which was significantly higher than that of ssDNA-FITC-hPAMAM without sonication. Additionally, the efficiency of transfection and the expression of the gus A gene were dependent on the N/P ratio and the highest efficiency (1.4%) was achieved at an N/P ratio of 10. The combination of 120 s of ultrasound and hPAMAM-DNA increased the gusA gene transfection and expression to 3.86%.

In this study, the effect of methyl jasmonate (MJ) and ultrasound (US), individually and in combination with L-tyrosine, on the stimulation of thebaine production in Papaver bracteatum cell suspension cultures was studied. The addition of L-tyrosine did not significantly affect the cell biomass, but significantly increased the thebaine yield of cells compared with the control. The synergistic effects of MJ and L-tyrosine in the combined treatment of 100 μM MJ and 2 mM L-tyrosine increased the thebaine yield of cells up to 84.62 mg L^− 1 at 6 days after treatment. Sonication of the cells for 20 s caused a significant decrease in cell growth and biomass, whereas the thebaine yield increased up to 39.60 mg L^− 1 at 6 days after treatment. The combination of US (10 s) and L-tyrosine feeding (2 mM) significantly increased the production of thebaine in comparison to individual utilisation of 2 mM L-tyrosine and US (10 s).