Effect of Green Synthesized ZnO-NPs on Growth, Antioxidant System Response and Bioactive Compound Accumulation in Echinops macrochaetus, a Potential Medicinal Plant, and Assessment of Genome Size (2C DNA Content)

Journal Article

2023

Echinops macrochaetus is a medicinal plant that can be used to cure various diseases. In
the present study, plant-mediated zinc oxide nanoparticles (ZnO-NPs) were synthesized using an
aqueous leaf extract of the medicinal plant Heliotropium bacciferum and characterized using various
techniques. E. macrochaetus was collected from the wild and identified using the internal transcribed
spacer sequence of nrDNA (ITS-nrDNA), which showed the closeness to its related genus in a
phylogenetic tree. The effect of synthesized biogenic ZnO-NPs was studied on E. macrochaetus in a
growth chamber for growth, bioactive compound enhancement and antioxidant system response.
The irrigation of plants at a low concentration of ZnO-NPs (T1 = 10 mg/L) induced more growth in
terms of biomass, chlorophyll content (273.11 g/g FW) and carotenoid content (135.61 g/g FW)
than the control and other treatments (T2-20 mg/L and T3-40 mg/L). However, the application of a
high concentration of ZnO-NPs (20 and 40 mg/L) increased the level of antioxidant enzymes (SOD,
APX and GR), total crude and soluble protein, proline and TBARS contents. The accumulations of
the compounds quercetin-3--D-glucoside, luteolin 7-rutinoside and p-coumaric acid were greater
in the leaf compared to the shoot and root. A minor variation was observed in genome size in
treated plants as compared to the control group. Overall, this study revealed the stimulatory effect of
phytomediated ZnO-NPs, which act as bio-stimulants/nano-fertilizers as revealed by more biomass
and the higher production of phytochemical compounds in different parts of the E. macrochaetus.