Cerium Oxide Nanoparticle Protects Maize from Cobalt Stress: Insights from Transcriptomics and Oxidative Stress Response Analysis

Nanozymes are a class of functional nanomaterials and
potential
next-generation artificial enzymes that exhibit catalytic properties.
However, their role against cobalt (Co) stress and the underlying
mechanisms remain largely unexplored. This study aimed to investigate
the potential of cerium oxide nanoparticles (CeO2 NPs as
nanozymes) against Co-induced stress in maize and to uncover the underlying
physiological and molecular mechanisms. Maize seeds were primed with
CeO2 NPs at 500 mg L–1 and exposed to
300 μM Co stress under hydroponic conditions. Results showed
that Co accumulated in the roots and is subsequently translocated
to aboveground tissues, affecting several key growth parameters in
maize plants. In contrast, CeO2 NPs alleviated these adverse
effects by enhancing growth and nutrient contents while reducing Co
uptake. Photosynthesis and antioxidant enzyme activities were increased,
while reactive oxygen species and malondialdehyde were reduced. Additionally,
RNA-Seq analysis revealed significant alterations in the expression
of key genes related to ion binding, metal transporters, and metabolite
biosynthesis, offering molecular evidence of their role under Co stress.
Notably, KEGG and GO analyses highlighted significant differences
in hormonal signaling, phenylpropanoid biosynthesis, and glutathione
metabolism in primed maize under Co stress. Taken together, this study
demonstrates that CeO2 NPs ameliorate Co toxicity in maize
by preserving leaf ultrastructure, enhancing antioxidant defense and
nutrient uptake, decreasing Co accumulation in roots and shoots, and
providing a promising nanozyme-based approach for maize protection
against Co-induced toxicity.