A single hormone, sprayed on leaves, may help one of the world’s most important food crops shrug off one of its newest pollutants. In a study published in the Journal of Advanced Research, researchers report that foliar applications of 24-epibrassinolide (EBL), a biologically active brassinosteroid, substantially alleviated the damage that polyethylene nanoplastics inflict on wheat, and that the protective effect reaches far beyond the leaf surface. Using a multi-omics strategy spanning physiology, metabolomics, spatial metabolite imaging, rhizosphere chemistry, and microbial community sequencing, the team showed that a leaf-applied signal restructures the root-soil interface itself, rebuilding metabolic balance in roots and reshaping the bacterial communities that surround them.
The problem the study addresses is growing rapidly. Polyethylene is the dominant polymer in agricultural mulching films, and field surveys of greenhouse and open-field soils have found that it accounts for roughly half of the microplastic polymers detected in farmland. Because polyethylene particles are light and have hydrophobic, weakly polar surfaces, they behave in distinctive ways in soil pores, modulating aggregation, retention, and transport at the soil-root boundary. Nanoplastics, defined as particles smaller than 100 nanometers, make up a substantial fraction of polyethylene debris, and wheat has proven particularly vulnerable: previous work by the same group showed that polyethylene nanoplastics significantly inhibit biomass accumulation in the crop, threatening both yield and quality.
Existing mitigation strategies fall into two broad camps. Soil-based approaches, such as biochar amendment, can reduce the mobility and toxicity of plastic particles through adsorption or immobilization, but their performance depends heavily on soil heterogeneity and amendment properties, limiting comparability and agronomic applicability. Plant-centered approaches, by contrast, offer a more controllable route. Exogenous melatonin, for example, has been shown to reduce nanoplastic uptake and toxicity in wheat. The researchers reasoned that brassinosteroids, which are known to stabilize photosynthetic machinery and reinforce antioxidant defenses under abiotic stress, might offer similar protection against nanoplastic stress, though this had never been tested.
The team grew wheat in greenhouse pots filled with soil treated with 50-nanometer polyethylene nanoplastics at 0.5 grams per kilogram, a concentration chosen from a prior dose-response study for producing pronounced, consistent stress. Three weeks after sowing, plants were sprayed three times, at three-day intervals, with EBL at 0.005, 0.05, or 0.5 milligrams per liter, doses anchored to label-recommended field dilution rates for wheat in China. Each treatment included six independent replicates, and strict precautions, including glass and stainless-steel tools and separate handling of control pots, minimized contamination from non-treatment plastics.
The results were striking. Nanoplastic exposure reduced shoot height by 13.4 percent and root length by 7.9 percent, and cut shoot and root fresh weights by 19.4 and 16.3 percent respectively. EBL alleviated these effects in a dose-dependent manner, with 0.05 milligrams per liter performing best: compared with nanoplastic-stressed plants, it increased shoot length by 6 percent, root length by 14 percent, shoot fresh weight by 16 percent, and root fresh weight by 32 percent. Photosynthesis, which nanoplastics depressed by 34 percent in net photosynthetic rate, rebounded by 73 percent under the same EBL treatment, alongside gains in maximum photochemical efficiency, total chlorophyll, carotenoids, stomatal conductance, and water use efficiency.
Oxidative stress told a parallel story. Nanoplastics raised malondialdehyde, a marker of lipid peroxidation, by 28 percent in leaves and 16 percent in roots while suppressing the antioxidant enzymes superoxide dismutase, catalase, and peroxidase. EBL at 0.05 milligrams per liter cut malondialdehyde back by 29 and 25 percent in leaves and roots and lifted enzyme activities by 18 to 26 percent. Mass spectrometry imaging further revealed that nanoplastics distorted phytohormone balance, elevating auxin, abscisic acid, and salicylic acid while suppressing jasmonic acid in both leaves and roots; EBL partially restored this balance, nearly doubling leaf jasmonic acid and reducing abscisic acid and salicylic acid substantially. Notably, root levels of endogenous brassinolide, which nanoplastics depressed, recovered after foliar spraying, evidence that a leaf-applied signal triggered a distal hormonal response below ground.
Untargeted root metabolomics using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry showed that nanoplastics downregulated 304 root metabolites and upregulated only 41. EBL treatment reversed much of this collapse, upregulating 383 metabolites relative to stressed plants, with pathway enrichment pointing to flavonoid biosynthesis, starch and sucrose metabolism, and purine metabolism. Spatial imaging added a crucial layer: nanoplastics concentrated sugar signals in the root apex, the actively growing zone, suggesting disrupted carbohydrate use, while EBL shifted sugars such as D-fructose toward more proximal regions and restored antioxidant flavonoids like quercetin derivatives and chlorogenic acid precisely where root-soil exchange occurs. Purine metabolism also rebounded, with reduced overaccumulation of ATP and GTP and renewed levels of ribose-5-phosphate, inosine, and AICAR, consistent with restored nucleotide turnover and energy balance.
The belowground effects extended into the rhizosphere itself. Rhizosphere soil chemistry shifted under EBL toward defense- and signaling-related metabolites, including higher levels of L-pipecolic acid, a central player in the systemic immune-priming pathway, along with methyl jasmonate, alliin, lauric acid, and LysoPC 18:3. Because these metabolites were extracted from non-sterile rhizosphere soil, the authors caution that they reflect integrated chemical signatures shaped by both plant inputs and microbial transformation rather than root exudation alone. Microbial sequencing of the 16S rRNA gene showed that nanoplastics increased Proteobacteria and Bacteroidota while depleting Actinobacteriota; EBL partially reversed these trends, enriching taxa such as Marmoricola and Gaiellales. Predicted functional profiles rose for methylotrophy, aromatic compound degradation, cellulolysis, and plastic-degradation-related processes, and EBL increased rhizosphere soil organic matter by 32 percent, available nitrogen by 14 percent, and available phosphorus by 20 percent while nudging pH upward.
A correlation network of 63 bacterial taxa, including Pseudomonas, Micromonospora, and Nocardioides, linked rhizosphere metabolites, root metabolites, and microbial assembly, with some taxa carrying intriguing credentials: Micromonospora has been associated with enhanced antioxidant metabolism in cereals, while Nocardioides includes hydrocarbon-degrading members isolated from plastic waste. The authors emphasize that these are candidate associations requiring strain-level validation, time-course experiments, and cross-soil comparisons with pristine and soil-aged particles. Even so, the study demonstrates that foliar EBL does not merely shield leaves; it coordinates aboveground-to-belowground regulation, reprogramming root metabolism, rhizosphere chemistry, microbial communities, and soil properties simultaneously.
The implications are considerable. As plastic contamination spreads through agricultural soils worldwide, hormone-based foliar treatments could offer a practical, scalable tool to protect staple crops without directly altering the soil matrix. The dose dependence matters too: the highest tested concentration, 0.5 milligrams per liter, actually caused photosynthetic and oxidative damage under non-stress conditions, underscoring that precision dosing at label-equivalent rates is essential. With wheat feeding more than half the global population, a leaf spray that rebuilds the rhizosphere’s metabolic and microbial architecture may prove a timely weapon against an invisible pollutant.
Subject of Research: Foliar 24-epibrassinolide mitigation of polyethylene nanoplastic stress in wheat through rhizosphere restructuring
Article Title: Rhizosphere micro-environment restructuring by foliar 24-epibrassinolide enhances wheat resilience to polyethylene nanoplastics
Article References: Zhuang, M., Zheng, X., Qiao, C., Han, L., Dun, J., Wang, S., Cao, M., Guo, L., Tian, F., & Wang, C. (2026). Rhizosphere micro-environment restructuring by foliar 24-epibrassinolide enhances wheat resilience to polyethylene nanoplastics. Journal of Advanced Research. https://doi.org/10.1016/j.jare.2026.09.010
Image Credits: AI Generated
DOI: 10.1016/j.jare.2026.09.010
Keywords: polyethylene nanoplastics, wheat, 24-epibrassinolide, brassinosteroids, rhizosphere, root metabolomics, mass spectrometry imaging, soil microbiome, oxidative stress, plant hormones, plastic pollution, crop resilience
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Alan Morgan. (September 23, 2026). Foliar Hormone Spray Helps Wheat Withstand Nanoplastic Pollution, Study Finds. Scienmag. https://scienmag.com/foliar-hormone-spray-helps-wheat-withstand-nanoplastic-pollution-study-finds/
Alan Morgan. “Foliar Hormone Spray Helps Wheat Withstand Nanoplastic Pollution, Study Finds.” Scienmag, 23 September 2026, https://scienmag.com/foliar-hormone-spray-helps-wheat-withstand-nanoplastic-pollution-study-finds/. Accessed 23 September 2026.
Alan Morgan. “Foliar Hormone Spray Helps Wheat Withstand Nanoplastic Pollution, Study Finds.” Scienmag. September 23, 2026. https://scienmag.com/foliar-hormone-spray-helps-wheat-withstand-nanoplastic-pollution-study-finds/
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Tags: 24-epibrassinolide24-epibrassinolide in agriculturebrassinosteroidscrop resilienceenvironmental stress mitigation in cropsfoliar hormone spray for crop resiliencemass spectrometry imagingmicrobial community shifts due to nanoplasticsmulti-omics analysis of plant responsenanoplastic pollution in farmlandnanoplastics impact on soil microbiomeOxidative stressplant hormone applications for pollution mitigationplant hormonesplastic pollutionpolyethylene nanoplasticspolyethylene nanoplastics effects on wheatrhizosphereroot metabolomicsroot-soil interface restructuringsoil microbiomesustainable agriculture and nanoplasticswheatwheat nanoplastic pollution
