The
increasing application of nanomaterials in agriculture raises
environmental risks, but the information on how nanomaterials impact
plant proteins is still limited. Here, we exposed the roots of rice
seedlings to CuO nanoparticles (NPs, 100 mg/L), CuO bulk particles
(BPs, 100 mg/L), and dissolved Cu ions (0.5 mg/L) for 14 days. The
results show that CuO NPs caused more Cu accumulation, higher ascorbate
peroxidase activity, and a higher ratio of GSH and GSSG but lower
activity of Mn-SOD than BPs and Cu ions. Isotopic multilabel relative
quantitative proteomics results indicate that NPs induced double differentially
expressed proteins compared to BPs and Cu ions, especially phosphoglycerate
kinase (fold change (FC) > 10) and glycosyltransferase (FC <
0.1).
Unlike BPs and Cu ions, the proteins that responded to NPs were primarily
connected with the C2 domain and glutathione S-transferase and significantly
enriched for drug metabolism and monovalent inorganic cation transport
processes and oxidative phosphorylation and phagosome pathways. Furthermore,
almost 20% of proteins in the protein–protein interaction belonged
to the ribosomal protein family. The parallel reaction monitoring
further proved the defense response to NPs involving in redox, signal
transduction, and heavy metal detoxification. Thus, proteomic analysis
suggests that CuO NPs caused higher phytotoxicity mainly due to the
nanospecific effect but elevated cysteine synthesis and GSSG reduction
for detoxification.