Application of nanoparticles (ZnO, TiO2 and CuO), a new opportunity for the stimulation of cell growth and azadirachtin production in cell suspension culture of Azadirachta indica

Nanoparticles have unique physicochemical properties and provide great opportunities in plant science studies. In this study, we investigated the impact of ZnO, TiO2 and CuO nanoparticles (0, 20, 40, 60, and 80 mg/L) and sampling times (2, 4, and 6 days) on cell suspension growth and azadirachtin accumulation and production. Factorial experiments based on a completely randomized design with three replications were used. Results demonstrated that different nanoparticles had a different effect on the studied characters. When ZnO nanoparticles were used, the highest fresh (540.73 g/L), dry cell weight (15.93 g/L), azadirachtin accumulation (5.15 mg/g DW) and production (68.27 mg/L) were obtained at control condition, 80 and 40 mg/L ZnO nanoparticles, and control condition after 6 days, respectively. The highest amount of fresh (526.95 g/L) and dry (17.05 g/L) cell weight and azadirachtin production (82.21 mg/L) and accumulation (5.93 mg/g DW) were observed in 20 mg/L TiO2 nanoparticles, 40 mg/L of TiO2 nanoparticles after 2 days, 20 mg/L TiO2 nanoparticles in 4 days and 60 mg/L of TiO2 nanoparticles, respectively. With applying CuO nanoparticles, the highest fresh cell weight and azadirachtin accumulation were 422.59 g/L and 4.00 mg/L, achieved in control conditions respectively. Also, the highest amount of azadirachtin production was 68.27 mg/L, observed in control conditions on the 6th day of treatment. It seems that suitable cell growth, except in some cases, occurred in the absence of elicitors, but azadirachtin accumulation and production were stimulated by nanoparticles treatment. However, the results showed that the CuO nanoparticles caused a decrease in overall azadirachtin accumulation and production in the cells.