Transcriptomic and mitochondrial functional analyses for quaternary ammonium iminofullerenes enhancing drought tolerance in maize.

Fullerene-based nanomaterials have been attested to enhance plant responses to abiotic stress, crop development, and crop production. Recently, quaternary ammonium iminofullerenes (IFQA), as nanobiostimulants, have played a positive role in protecting maize against drought stress through reactive oxygen species (ROS) neutralization and maintenance of energy status. However, there is a lack of knowledge regarding IFQA-mediated molecular mechanism and its efficacy in mitochondrial homeostasis in drought-stress maize seedlings. In this study, mitochondrial structure and functional homeostasis analysis and transcriptome profiling of maize roots exposed to H2O and solutions of polyethylene glycol (PEG), IFQA, and PEG + IFQA were performed to investigate the IFQA-mediated maize response to drought stress at molecular level. Transcriptome profiling indicated that IFQA affected the expression of genes related to redox reactions, hormone signaling, and energy and secondary metabolisms. Mitochondrial homeostasis analysis revealed that IFQA can restore mitochondrial ultrastructure and membrane potential to inhibit PEG-induced ROS overaccumulation. These are valuable insights into the protective roles of exogenous IFQA and its molecular mechanism in alleviating drought stress in maize, partially via the activation of antioxidants and modulation of energy metabolic homeostasis. It provides further evidence that carbon-based nanomaterials have potential application in sustainably improving stress tolerance and climate resilience in crops.