Engineered ZnO and CuO Nanoparticles Ameliorate Morphological and Biochemical Response in Tissue Culture Regenerants of Candyleaf (Stevia rebaudiana)

Abstract

Sustainable production of secondary metabolites in medicinal plants by artificial culturing on the industrial scale has gained worldwide importance. Engineered nanoparticles (ENPs) play a pivotal role in the elicitation of compounds of medicinal value. This investigation explores the influence of ZnO and CuO ENPs on in vitro roots formation, non-enzymatic antioxidant activities, and production of steviol glycosides (SGs) in regenerants of Candyleaf, Stevia rebaudiana. ENPs were applied in 0, 2, 20, 200, and 2000 mg/L of concentration in the MS medium containing plant shoots. The percentage of rooting induced was 91% and 94% by applying ZnO ENPs (2 mg/L) and CuO ENPs (20 mg/L), respectively. Moreover, at 2 mg/L of ZnO and 20 mg/L of CuO ENPs, the high performance liquid chromatography studies determined the significantly greatest content of SGs; rebaudioside A (4.42 and 4.44) and stevioside (1.28 and 1.96). Phytochemical studies including total flavonoid content, total phenolic content, and 2,2-diphenyl-1-picryl hydrazyl-free radical scavenging activity were calculated highest by the regenerants grown in 2 mg/L of ZnO and 20 mg/L of CuO ENPs dosage. Both ZnO and CuO ENPs at 200 mg/L and 2000 mg/L of concentration induced adverse effects on plant biomass, antioxidant activities, and SGs content up to 1.22 and 1.77 for rebaudioside A and 0.21 and 0.25 for stevioside. Hence, the biochemical and morphophysiological responses of Candyleaf were elicited as a defense against ZnO and CuO ENPs applied under threshold limit. This artificial biotechnological technique holds great promise for continued production of natural antioxidants on commercial scale and our study has further strengthened this impact.

Nanoparticles as Novel Elicitors to Improve Bioactive Compounds in Plants

“…A comparative study of NPs effects is the enhance of α-tocopherol in vitro production of Argan using TiO 2 NPs and Silicon Dioxide (SiO 2 ) NPs as elicitors are reported in both NPs a concentration of 5 ppm with SiO 2 NPs as mayor effect (4.59 and 4.7 fold of the control respectively) [73]. Ahmad et al [69] studied ZnO and CuO NPs elicitation in candy leaf; they reported an increase of rebaudioside A (4.42%), stevioside content (1.28%), total phenolic content (5.86 µg gallic acid equivalent/mg), total flavonoid content (6.25 µg QE/mg), total antioxidant activity (9.09 µg AAE/mg), total reducing power (11.04 µg AAE/mg) and % DPPH inhibition (75.6%) treatment with 2 mg/L of ZnO. Under the elicitation of CuO NPs, the authors reported an increment of total phenolic content (4.55 µg gallic acid equivalent/mg), total flavonoid content (5.67 µg QE/mg), total antioxidant activity (10.05 µg AAE/mg), total reducing power (12.04 µg AAE/mg) and % DPPH inhibition (75.6%) treatment with 20 mg/L [69].…”

Advances and Perspectives in Tissue Culture and Genetic Engineering of Cannabis

“…Therefore, the application of SNP may pave the way for obtaining somatic embryogenesis or improving organogenesis protocols in cannabis. Recent studies showed that adding nanoparticles to the culture media improves callogenesis, organogenesis, somatic embryogenesis, and rhizogenesis by inhibiting the production of ROS and ethylene and altering gene expression and antioxidant enzyme activities [ 100 , 101 , 102 , 103 , 104 , 105 ]. Thus, the application of nanoparticles can be investigated as a promising approach to enhance the in vitro regeneration capacity of cannabis.…”

PEG 6000-Stimulated Drought Stress Improves the Attributes of In Vitro Growth, Steviol Glycosides Production, and Antioxidant Activities in Stevia rebaudiana Bertoni

“…Seeds of S. rebaudiana show poor germination and the conventional propagation strategies such as cuttings are not effective [5]. Hence, new biotechnological approaches have been adopted for maximum production of Stevia progeny and its medicinal components in the minimum period of time [6][7][8][9][10][11][12][13].…”