Identifying the Phytotoxicity and Defense Mechanisms Associated with Graphene-Based Nanomaterials by Integrating Multiomics and Regular Analysis

Abstract

The application of graphene-based nanomaterials (GBNs) has attracted global attention in various fields, and understanding defense mechanisms against the phytotoxicity of GBNs is crucial for assessing their environmental risks and safe-by-design. However, the related information is lacking, especially for edible vegetable crops. In the present study, GBNs (0.25, 2.5, and 25 mg/kg plant fresh weight) were injected into the stems of pepper plants. The results showed that the plant defense was regulated by reducing the calcium content by 21.7–48.3%, intercellular CO2 concentration by 12.0–35.2%, transpiration rate by 8.7–40.2%, and stomatal conductance by 16.9–50.5%. The defense pathways of plants in response to stress were further verified by the downregulation of endocytosis and transmembrane transport proteins, leading to a decrease in the nanomaterial uptake. The phytohormone gibberellin and abscisic acid receptor PYL8 were upregulated, indicating the activation of defense systems. However, reduced graphene oxide and graphene oxide quantum dots trigger stronger oxidative stress (e.g., H2O2 and malondialdehyde) than graphene oxide in fruits due to the breakdown of antioxidant defense systems (e.g., cytochrome P450 86A22 and P450 77A1). Both nontargeted proteomics and metabolomics consistently demonstrated that the downregulation of carbohydrate and upregulation of amino acid metabolism were the main mechanisms underlying the phytotoxicity and defense mechanisms, respectively.

Long-Term Exposure of Graphene Oxide Suspension to Air Leading to Spontaneous Radical-Driven Degradation

“…The global market for GO products will be approximately US$ 200–2,000 million by 2025 . The growing industrial and domestic demands of GO have increased its production, use, disposal, environmental release, and accumulation, leading to potential risks to the ecological environment and human health. , Therefore, to progress legislation and commercial acceptance, it is necessary to evaluate and understand the environment’s transformation, fate, and toxicity.…”

Particle Size Determines the Phytotoxicity of ZnO Nanoparticles in Rice (Oryza sativa L.) Revealed by Spatial Imaging Techniques

“…Consequently, excess ROS would further attack biological macromolecules, causing the damage to cytomembranes and increasing the lipid peroxide (MDA) content. 51 In this study, the MDA content in rice roots increased gradually with the increase in the ZnO NP concentration, indicating that the balance between the generation and elimination of ROS was disrupted in the seedlings under stress. Recent studies have highlighted the role of ZnO NPs in inducing the generation of ROS.…”

“…When plants were under severe stress, a high concentration of ROS would exceed the scavenging capacity of the antioxidant system. Consequently, excess ROS would further attack biological macromolecules, causing the damage to cytomembranes and increasing the lipid peroxide (MDA) content . In this study, the MDA content in rice roots increased gradually with the increase in the ZnO NP concentration, indicating that the balance between the generation and elimination of ROS was disrupted in the seedlings under stress.…”

“…Furthermore, the effects of NPs on plant cells can exhibit dose-dependent effects, with doses above essential levels potentially causing increased toxicity . Nanotoxicity can cause plant physiological and biochemical changes such as in the oxidative stress response, gene expression, and metabolism in tissues. − However, it is doubtful whether plant nanotoxicity follows the same size effect as nanotoxicity in animals. To clarify this point, a systematic investigation is needed to verify the stoichiometric relationship between NP size and phytotoxicity to understand the biosecurity of NPs in agricultural applications.…”

Advances in Biologically Applicable Graphene-Based 2D Nanomaterials

“…On the other hand, the activation of defense system was reflected in upregulation of gibberellin and abscisic acid receptor PYL8. Higher levels of the oxidative stress in fruits were observed using rGO and GOQDs compared to GO, and in the phytotoxicity and defense mechanisms, downregulation of carbohydrate and upregulation of amino acid metabolism played the crucial role [ 204 ]. On the other hand, surface-oxygen content affecting the biological impacts was found to be crucial factor for the phytotoxic impact of GR nanomaterials.…”