In vitro effect of nanoparticles on sugar beet (Beta vulgaris) and its secondary metabolites (betalain and betaine) production

Sugar beet (Beta vulgaris L.) is considered the most desirable and productive economic and food crop. Many studies have been based on the development of this crop. With the widespread applications of nanoparticles in the field of plants that have received great interest, due to their amazing results and promising capabilities that are considered so far only the "tip of the iceberg", this research was conducted to investigate the effect of two nanoparticles on the sugar beet plants in several respects; seed germination, morphology, chlorophyll A and B content, and carotenoids, as well as two of the most important sugar beet metabolites, betaine and betalain. TiO2 NPs and ZnO NPs were applied in four different concentrations separately (0, 5, 15, and 25 mg/ml) on two genotypes of sugar beet plants, monogerm (SG833) and multigerm (SG2020), by adding the NPs to the MS medium. Using a UV-spectrophotometer, chlorophyll, carotenoids, betaine, and betalain were estimated. Plants exposed to NPs did not have a significant difference in terms of seed germination, chlorophyll contents, or carotenoids compared to the control. In comparison to the control group, it showed a statistically significant difference and improvement for betaine at low concentrations of NPs and gradually decreased with increasing concentrations in both genotypes. In contrast to the multigerm genotype (SG2020), which showed a statistically significant increase in the content of betaxanthin at a concentration of 15 mg/ml (p<0.01) and 25 mg/ml (p<0.05) of ZnO NPs compared to the control. Regarding betacyanin, only the plants exposed to ZnO NPs at the highest concentration, which is 25 mg/mL, showed a statistically significant increase (p< 0.05), compared to the control plants. It is indicated that the response of plants during exposure to NPs depends on several factors, including the type of nanoparticles, their concentration, and the exposure time; moreover, it varies between plant species and even between genotypes within the same plant species.