CuO and ZnO Nanoparticles Modify Interkingdom Cell Signaling Processes Relevant to Crop Production

Abstract

As the world population increases, strategies for sustainable agriculture are needed to fulfill the global need for plants for food and other commercial products. Nanoparticle formulations are likely to be part of the developing strategies. CuO and ZnO nanoparticles (NPs) offer potential as fertilizers, as they provide bioavailable essential metals, and as pesticides, because of dose-dependent toxicity. Effects of these metal oxide NPs on rhizosphere functions are the focus of this review. These NPs at doses of ≥10 mg metal/kg change the production of key metabolites involved in plant protection in a root-associated microbe, Pseudomonas chlororaphis O6. Altered synthesis occurs in the microbe for phenazines, which function in plant resistance to pathogens, the pyoverdine-like siderophore that enhances Fe bioavailability in the rhizosphere and indole-3-acetic acid affecting plant growth. In wheat seedlings, reprogramming of root morphology involves increases in root hair proliferation (CuO NPs) and lateral root formation (ZnO NPs). Systemic changes in wheat shoot gene expression point to altered regulation for metal stress resilience as well as the potential for enhanced survival under stress commonly encountered in the field. These responses to the NPs cross kingdoms involving the bacteria, fungi, and plants in the rhizosphere. Our challenge is to learn how to understand the value of these potential changes and successfully formulate the NPs for optimal activity in the rhizosphere of crop plants. These formulations may be integrated into developing practices to ensure the sustainability of crop production.

Facile Coating of Urea With Low-Dose ZnO Nanoparticles Promotes Wheat Performance and Enhances Zn Uptake Under Drought Stress

“…This is as a result of the enhanced reactivity of nanoparticles arising from their small size and greater surface area, compared to bulk particles. Such heightened or nanoscale-specific effects have been observed in microbes, plants, and other terrestrial species (Dimkpa et al, 2012b;Dimkpa, 2014;Anderson et al, 2018;Rajput et al, 2018). In addition to greater nanoscale reactivity, the degree of the effects of ZnO-NPs also depends on dose, plant species and age, exposure route and duration, and environmental conditions such as pH and surface interactions with other soil components (Jośko and Oleszczuk, 2013;Watson et al, 2015;Mukherjee et al, 2016;García-Gómez et al, 2017;Dimkpa et al, 2019a).…”

Differential Expression of Mitochondrial Manganese Superoxide Dismutase (SOD) in Triticum aestivum Exposed to Silver Nitrate and Silver Nanoparticles

“…Based on literature there is no full understanding of the potential for health or environmental risks on nanoparticles (5). The eff ects of metal nanoparticles on plant germination and growth with focus on crop yield have been reported elsewhere (6)(7)(8)(9)(10). In contrast, possible side eff ects of the use of silver nanoparticles and silver ions on plant growth has received little attention (11)(12)(13)(14).…”

The Power of Being Small: Nanosized Products for Agriculture

“…For example, ZnO NPs induce formation of a metal-chelating siderophore, but reduce production of antifungal phenazines (Goodman et al, 2016). Significantly, the ZnO NPs impair production of the acyl homoserine lactones, which are signals regulating the production of these and other metabolites with functions in the rhizosphere (Anderson et al, 2017a;Goodman et al, 2016). Increased production of the pseudomonad siderophore is observed from wheat roots colonized by P. chlororaphis O6 when growing with ZnO NPs (Dimkpa et al, 2015a).…”