Assessment of the Effect of Optical Spectra (LED) and TiO2 and ZnO Nanoparticles on Vegetative Embryogenesis and Regeneration of Some Ecotypes in Ajowan (Trachyspermum ammi L.)

Ajowan (Trachyspermum ammi L) belongs to the Apiaceae family. Using plant tissue culture techniques, plant genetic diversity can be conserved in a controlled environment. The aim of the present study was to investigate the effect of different concentrations of ZnO and TiO2 nanoparticles and light qualities on somatic embryogenesis of ajowan and regeneration. The present experiment was framed in factorial (factors including ecotype, nanoparticles, optical spectrum) based on completely randomized design in three replicates. After the addition of nanoparticles to the MS medium, the explants were placed under red, blue, and light spectra and combined of them. The results showed that the use of ZnO and TiO2 nanoparticles reduced the percentage of fungal and bacterial contamination compared to the control treatment. With increasing the concentration of TiO2 nanoparticles under blue and red spectra, there was no contamination. Also, the highest rate of callogenesis, somatic embryogenesis and regeneration was obtained in Shiraz and Ardebil ecotypes with TiO2 nanoparticle under the combinational use of blue and red spectra. The blue light spectrum had the greatest effect on the control of contamination using ZnO nanoparticle. The formation of embryonic cells increased in TiO2 culture medium with a concentration of 10 mg L-1 under the combinational use of blue and red lights. With increasing nanoparticle concentration and light intensity, the accumulation of free radicals and activity of polyphenol oxidase were inhibited and the nutrient uptake by growing cells increased. In contrast, the regenerated control plants turned into white mass and causing the death of embryogenic calli, and seedlings. This study, using TiO2 and ZnO nanoparticles, it was possible to present an effective and useful protocol for induction of vegetative embryo and regeneration in the shortest time in the culture medium.