Graphene oxide nanoparticles boost growth development, grain anthocyanins accumulation and coloration formation of...

Microplastics are ubiquitous pollutants, presenting a potential threat to plant growth, health and products quality. Graphene oxide (GO), serving as a nanomaterial for modern agriculture, has been widely known to play important roles in alleviating the effect of hazard materials. However, it remains unexplored about its role in reducing polyvinyl chloride microplastics (PVC-MPs) toxicity in maize. Here, we systematically examined the effects of different treatments of individual PVC and GO, as well as the combined PVC+GO on the growth, physiological responses, yield, and grain quality of purple waxy maize. Notably, the seedling growth inhibition under 0.25 % PVC-MPs pollution was strongly relieved by application with 5.0 mg/kg GO. PVC+5.0GO co-exposure resulted in the significant increase of ear length, diameter and weight, and clearly inducing grain coloration and total anthocyanin accumulation (44.89 %) at 30 days after pollination (30 DAP). Moreover, PVC+ 5.0GO treatment evidently alleviated the activities of anthocyanin degradation enzymes, especially peroxidase (45.61 %) and polyphenol oxidase (20.21 %), compared to PVC treatment alone at 30 DAP. RNA-sequencing analysis clearly showed that the "anthocyanin biosynthesis", "flavonoid biosynthesis", and "flavone and flavonol biosynthesis" pathways were strongly enriched. Meanwhile, 36, 25, and 41 candidate genes involved in anthocyanin biosynthesis, transport, and degradation were further identified, respectively. Moreover, co-expression network analysis revealed that three key modules containing 44 genes, were correlated with anthocyanin metabolism activated by PVC+5.0GO, among which MYB83-bHLH7-WD40 (MBW) module was identified to play an important role in regulating anthocyanin biosynthesis during grain development. Overall, the data revealed that GO could enhance the waxy maize resilience to PVC-MPs pollution.