RAPD Marker Associations and Antioxidant Enzyme Responses of Houttuynia cordata Germplasms Under Lead Stress

Houttuynia cordata, a characteristic edible and medicinal vegetable in southwestern China, is prone to absorbing lead (Pb2+). Excessive consumption may lead to Pb²⁺ accumulation in the human body, which has been linked to serious health risks such as neurotoxicity, kidney damage, anemia, and developmental disorders, particularly in children. Therefore, development of molecular markers associated with Pb2+ uptake and the investigation of the plant’s physiological responses to Pb²⁺ pollution are of great significance. In this study, 72 H. cordata germplasms were evaluated for Pb2+ accumulation after exogenous Pb²⁺ treatment. A significant variation in Pb²⁺ content was observed among the germplasms, indicating rich genetic diversity. Using RAPD markers, seven loci were identified to be significantly associated with Pb²⁺ uptake, with locus 43 (R² = 6.72%) and locus 53 (R² = 5.39%) showing the strongest correlations. Marker validation was performed using five low- and five high-accumulating accessions.Two representative germplasms were further subjected to 0, 500, and 1500 mg/kg Pb²⁺ treatments for 40 days. Pb²⁺ content, membrane lipid peroxidation, and redox enzyme activities (SOD, POD and CAT) were measured across different organs. Organs with greater soil contact (roots) exhibited higher Pb²⁺ accumulation and oxidative damage. POD and CAT activities were markedly induced by Pb²⁺ stress, while SOD response was limited.This study provides a theoretical foundation for breeding low Pb²⁺-accumulating H. cordata varieties through marker-assisted selection (MAS) and supports their safe use and application in phytoremediation.