Regulatory Mechanism of Copper Oxide Nanoparticles on Uptake of Different Species of Arsenic in Rice

Abstract

Copper oxide nanoparticles (CuO NPs) are widely used as a fungicide in agriculture. The application of CuO NPs in agriculture affects the growth of rice and metal accumulation in rice. However, the mechanism of CuO NPs on arsenic (As) accumulation in rice remains unclear. In this study, a hydroponic culture was produced to investigate the mechanism of the effect of 50 and 100 mg L−1 CuO NPs on As accumulation in rice. Our results showed that CuO NPs decreased As(III/V) accumulation in the roots and shoots by adsorbing As(III/V), oxidizing of As(III) on the surface, and thickening the root cell wall. The addition of CuO NPs regulated the expression of the OsNIP1;1, OsHAC1;1, and OsHAC4 genes, which decreased As(III) transport and promoted As(V) reduction in the roots. Moreover, when CuO NPs were co-exposed to As, a negative correlation between the concentration of Cu and As in rice was also found in our study. However, CuO NPs significantly increased Cu accumulation in rice and constrained the rice growth. In conclusion, CuO NPs might be a promising way to decrease As accumulation in rice, but the negative effects such as growth inhibition should be further considered. Therefore, the application of CuO NPs in rice plants should take a more restrained approach.

Impact of Three Copper Amendments on Arsenic Accumulation and Speciation in Rice (Oryza sativa L.) in a Life Cycle Study

“…All three forms of Cu significantly decreased As­(III) and organic As species, especially monomethylarsonic acid (MMA­(V)) and arsenobetaine in rice shoot tissues at both growth stages. The decreased As­(III) in rice shoots was consistent with previous short-term hydroponic studies with CuONPs. , Both CuONPs and CuOBPs display high adsorption capacity for As, which might decrease the bioavailability of As. − It has also been reported that As­(III) could be oxidized to As­(V) on the surface of CuONPs accompanied with the reduction of Cu 2+ to Cu + or by reactive oxygen species (ROS) induced by free Cu + . ,, For Cu ions, the significantly higher As retention in rice roots might be related to the defense mechanisms of plants to form Cu 2+ -plant root exudate complexes, which are sequestered into vacuoles of root cells, together with As. ,, This higher root As retention decreased As transfer from roots to shoots.…”

“…Several studies indicated that the adsorption of As­(III/V) onto CuONPs is one of the main reasons causing As immobilization and decreased As bioavailability in the growth media. , Another important mechanism is the oxidation of As­(III) to As­(V) on the surface of CuONPs, which could lower the As availability and toxicity. , The addition of CuONPs was also reported to thicken the rice root cell wall and upregulate the expression of OsNIP1;1 , OsHAC1;1 , and OsHAC4 . The upregulated OsHAC1;1 and OsHAC4 as the As­(V) reductase could enhance As­(V) reduction and detoxification in rice roots, , while OsNIP1;1 could decrease the root-to-shoot translocation of As­(III) .…”

Effects and Mechanisms of Copper Oxide Nanoparticles with Regard to Arsenic Availability in Soil–Rice Systems: Adsorption Behavior and Microbial Response

“…Experimental materials of CuO NPs were purchased from Beijing NaChen Technology Co. Ltd. The morphology, particle size, ζ potential, and elemental composition of CuO NPs were reported in a previous study. , Arsenic-rich soil was collected from the surface (0–20 cm) of paddy fields around a mining area (119°46′E, 29°59′N) located in Shangyu, Zhejiang Province, China. The contaminated soil was air-dried in a greenhouse and then passed through a 2 mm nylon sieve.…”

Application and mechanisms of metal‐based nanoparticles in the control of bacterial and fungal crop diseases

“…32,39,40 Several studies have confirmed that the application of moderate concentrations of Cu NPs or CuO NPs can promote the growth of certain plants, increase the uptake of nutrients such as Cu and S, and reduce the uptake of heavy metal elements by plants. [41][42][43] In addition to their beneficial effects on plants, Cu NPs can also inhibit the growth of pathogens (Table 1) such as bacteria Pseudomonas aeruginosa, Staphylococcus aureus and fungi Candida albicans. 44 For some fungi that lead to crop soil-borne diseases, Cu NPs showed superior inhibition to CuO NPs.…”

“…Copper nanoparticles for plant research include zero‐valent Cu nanoparticles (Cu NPs), CuO nanoparticles (CuO NPs) and Cu nanocomposites 32,39,40 . Several studies have confirmed that the application of moderate concentrations of Cu NPs or CuO NPs can promote the growth of certain plants, increase the uptake of nutrients such as Cu and S, and reduce the uptake of heavy metal elements by plants 41–43 …”