Star Polymers with Designed Reactive Oxygen Species Scavenging and Agent Delivery Functionality Promote Plant Stress Tolerance

Abstract

Plant abiotic stress induces reactive oxygen species (ROS) accumulation in leaves that can decrease photosynthetic performance and crop yield. Materials that scavenge ROS and simultaneously provide nutrients in vivo are needed to manage this stress. Here, we incorporated both ROS scavenging and ROS triggered agent release functionality into an ∼20 nm ROS responsive star polymer (RSP) poly(acrylic acid)-block-poly((2-(methylsulfinyl)ethyl acrylate)-co-(2-(methylthio)ethyl acrylate)) (PAA-b-P(MSEA-co-MTEA)) that alleviated plant stress by simultaneous ROS scavenging and nutrient agent release. Hyperspectral imaging indicates that all of the RSP penetrates through the tomato leaf epidermis, and 32.7% of the applied RSP associates with chloroplasts in mesophyll. RSP scavenged up to 10 μmol mg −1 ROS in vitro and suppressed ROS in vivo in stressed tomato (Solanum lycopersicum) leaves. Reaction of the RSP with H 2 O 2 in vitro enhanced the release of nutrient agent (Mg 2+ ) from star polymers. Foliar applied RSP increased photosynthesis in plants under heat and light stress compared to untreated controls, enhancing the carbon assimilation, quantum yield of CO 2 assimilation, Rubisco carboxylation rate, and photosystem II quantum yield. Mg loaded RSP improved photosynthesis in Mg deficient plants, mainly by promoting Rubisco activity. These results indicate the potential of ROS scavenging nanocarriers like RSP to alleviate abiotic stress in crop plants, allowing crop plants to be more resilient to heat stress, and potentially other climate change induced abiotic stressors.

Nanobiotechnology-based strategies for enhanced crop stress resilience

“…In addition to directly acting as ROS-scavenger, NMs can act as carriers to deliver ROS-eliminating compounds to enhance plant stress tolerance. The authors of a recent study 28 designed an ROS-responsive star polymer (RSP) that successfully alleviated plant stress by simultaneous ROS-quenching and nutrient release. Specifically, RSP was foliar-applied to stressed tomato (Solanum lycopersicum) leaves.…”

Recent advances in the design of controlled- and sustained-release micro/nanocarriers of pesticide

“…[29][30][31] The modified nanomaterials also provide other benefits including enhanced leaf adhesion and flush resistance to placate various pressing biotic and abiotic stresses (for example, heat, drought, salinity excess, light, drought and nutrient deficiency). 11,[32][33][34] Metal materials, mesoporous silicon nanoparticles (MSNs), 35,36 carbon nanotubes, 37 biochar 16 and synthetic polymers are commonly used to construct carriers due to their large specific surface area and high porosity. In addition, natural polymers (e.g., lignin, cellulose, lipid) with good renewability and biocompatibility have been used to construct controlled-and sustainedrelease micro/nanocarriers.…”

Temperature-Responsive Bottlebrush Polymers Deliver a Stress-Regulating Agent In Vivo for Prolonged Plant Heat Stress Mitigation

“…Foliar application of active agents is another potential solution. − For example, anionic cerium oxide nanoparticles (NPs) infiltrated into Arabidopsis thaliana leaves scavenged reactive oxygen species (ROS) in plants and alleviated heat stress . Foliar-applied ROS responsive star polymers scavenged ROS and delivered magnesium to chloroplasts, which improved plant stress tolerance . Plant stress-regulating agents such as glycine betaine, spermidine, and salicylic acid can also mitigate plant heat stress after foliar application − but only provide short-term benefits and need to be applied during the stress event which can be difficult to predict precisely. , Longer-term stress tolerance would require frequent and continuous active agent application, which generates more waste and increases application costs .…”