Mechanistic investigation of the associations between bacterial community composition and cadmium distribution in Zizania latifolia

The role of bacteria in external niches regulating cadmium (Cd(II)) in plant tissues remains unclear. We explored Cd(II) profiles and identified bacterial contributors among phyllosphere, rhizoplane, and rhizosphere of four Zizania latifolia varieties through integrated metagenomic and chemical analyses. Zizania latifolia accumulated Cd(II) in leaves (0.06–0.77 mg/kg), roots (0.73–1.57 mg/kg), and rhizosphere (0.43–3.15 mg/kg), respectively. The highest enrichment coefficient (leaf-Cd(II)/soil-Cd(II)) was observed in Genotype 3 (0.6). Among top 10 genus-level bacteria, Enterococcus in phyllosphere, Streptomyces and Dechloromonas in rhizoplane, and Bradyrhizobium , Pseudolabrys , Mycobacterium , and Dechloromonas in rhizosphere were significantly related to Cd(II). Enterococcus adsorbed Cd(II) by extracellular polysaccharides and precipitated Cd(II) sulfide. Rhizoplane and rhizosphere bacteria absorbed Cd(II) by cell-surface functional groups, and fixed Cd(II) through synthesizing polyphosphate and driving Fe (II) oxidation. Additionally, 64.4%-80% of bacteria were shared between rhizoplane and rhizosphere, 5.5%-6.9% between rhizoplane and phyllosphere, and 4.4%-6.1% between rhizosphere and phyllosphere. Metagenomic analysis indicated that Cd(II) disturbed bacterial secretion system and amino acid metabolic pathways. These findings provided comprehensive insights into interrelationships between Cd(II) and bacteria in leaves, roots, and rhizosphere of Zizania latifolia , offering valuable foundations for developing targeted strategies to mitigate Cd(II) accumulation in aquatic vegetables. • Zizania latifolia leaves exhibit remarkably strong capacities for Cd accumulation. • Enterococcus is related with leaf Cd. • Streptomyces and Dechloromonas are associated with root Cd. • Bradyrhizobium and Pseudolabrys affect rhizosphere Cd. • Shared bacteria in phyllosphere, rhizoplane, and rhizosphere correlae with Cd.