Grapevine rootstocks are a promising strategy for phytostabilization in soils contaminated with cadmium

Abstract

Cadmium (Cd) contamination in vineyard soils poses a significant threat to viticulture and food security, yet the physiological and molecular mechanisms governing rootstock responses remain insufficiently understood. This study investigated the impact of Cd on six grapevine rootstocks (Kanzhen 3, SO4, 3309 M, 5BB, 101–14, and Beida) to evaluate their tolerance and mitigation potential. Plants were exposed to soil Cd concentrations ranging from 0 to 20 mg kg⁻¹ for 28 days, with morphological, anatomical, and distribution parameters measured. Additionally, to elucidate the molecular basis of differential tolerance, the expression profiles of 14 major stress-responsive genes were analyzed in the contrasting genotypes ‘101–14’ (sensitive) and ‘SO4’ (tolerant) under high-stress conditions (20 mg kg⁻¹). Physiologically, increasing Cd concentrations significantly inhibited plant height, root length, and biomass across all tissues, with accumulation highest in roots. High exposure caused root structural damage and stomatal closure. Molecular analysis revealed a distinct, genotype-dependent transcriptional response; the tolerant ‘SO4’ genotype exhibited a swift, coordinated upregulation of genes essential for antioxidant defense (VvSOD, VvCAT, VvAPX), flavonoid biosynthesis (VvCHS1, VvSTS1), and detoxification (VvGST4, VvABCC1). Conversely, the sensitive ‘101–14’ genotype displayed a constrained transcriptional response with minimal induction of key defense genes. Translocation and bioconcentration factors were consistently below 1, classifying all rootstocks as “metal excluders” suitable for phytostabilization. Among the tested genotypes, ‘SO4’ and ‘3309 M’ were the most effective at limiting Cd uptake. These findings suggest that Cd toxicity is dose-dependent and that the superior tolerance of SO4 is associated with coordinated upregulation of antioxidant and detoxification genes. Consequently, selecting tolerant rootstocks represents a promising strategy for remediation, though further research under fruiting conditions is required to ensure long-term food safety.