Phytotoxicity of high-dose graphene oxide in cotton seedlings: A multi-omics reveal of molecular and physiological responses

Graphene oxide (GO), a widely used nanomaterial known for its unique physical and chemical properties, has raised increasing concerns about its potential environmental risks, particularly its phytotoxicity. Cotton, as an economically important non-food crop that does not enter the human food chain and has inherent advantages in soil pollution remediation, makes it an ideal model organism for assessing the environmental impact of GO. Here, we present the first multi-omics analysis integrating morpho-physiological, epigenetic, transcriptomic, and metabolomic approaches to elucidate the mechanisms of GO-induced stress in cotton seedlings. Exposure to high concentrations of GO (250 and 500 mg/L) caused dose-dependent growth inhibition, excessive accumulation of reactive oxygen species, and activation of antioxidant defenses. Transmission electron microscopy revealed the penetration of GO into root tissues and its translocation to aerial parts. Integrative multi-omics analyses revealed extensive transcriptional reprogramming, partially regulated by epigenetic modifications, accompanied by disruptions in key metabolic pathways such as phenylpropanoid and flavonoid biosynthesis, ABC transporters, and tryptophan metabolism. This study provides mechanistic insights into how cotton reallocates energy and metabolic resources from growth to defense under nanomaterial stress, establishing a framework for evaluating the sustainability and ecological safety of nanomaterials in agriculture.