Electrochemical and molecular mechanisms underlying aluminum-enhanced copper homeostasis in maize roots within acidic...

Copper (Cu)-contaminated soils near mining areas are typically strongly acidic, triggering substantial release of reactive aluminum (Al) from solid phases. However, Al-Cu bio-interaction effects remain understudied, despite their potential critical role. This study employed short- and long-term hydroponic experiments, along with pot trials using a Cu-contaminated soil, to investigate Al co-stress effects on Cu uptake and translocation. A multiscale approach integrating the streaming potential, zeta potential, and surface electrical potential was employed to characterize charge properties across the root surface-cell wall-cell membrane continuum. Advanced spectroscopic and metabolic techniques were integrated to elucidate the electrochemical and molecular mechanisms underlying Al-mediated Cu uptake. Results showed that Al co-stress reduced the amount of exchangeable Cu on maize root surfaces and inhibited its absorption and translocation. The coordinated decrease in electronegativity and functional group abundance of root continuum was the key electrochemical adaptation mechanism. D-galactose, malate and trehalose were critical regulators of hemicellulose biosynthesis and cell wall remodeling. Disorders in sugar-lipid and glutathione metabolism activated energy-priority survival strategy, prioritizing the synthesis of energy-efficient and persistent antioxidants (e.g. vitexin) and nucleotide to sustain cellular homeostasis. This study provides potential target metabolites and electronegativity adjustment strategies for improving crop adaptation to acidic polluted environments.