Cadmium distinctly affects selenium accumulation in Cardamine violifolia roots and shoots

While selenium (Se) antagonism on cadmium (Cd) uptake in plants has been extensively studied, the reciprocal regulatory mechanisms governing Cd-mediated Se accumulation remain poorly characterized. This investigation utilized the Se hyperaccumulator Cardamine violifolia to elucidate these interactions. The results demonstrated that Cd exposure increased root hair formation, promoted Se concentrations in the roots but reduced its shoot accumulation . Both Cd and Se were deposited in the leaf margins. Transcriptome analysis showed that the expressions of adenosine-5′-phosphosulfate kinase ( APK1 , APK2 , and APK4 ) and adenosine 5′-phosphosulfate reductase ( APR1 and APR3 ) were induced by Cd in the shoots; six sulfate transporters, including inorganic phosphate transporter 1.3 ( PHT1.3 ) and sulfate transporter 1.2 ( SULTR1.2 ) exhibited coordinated expression modulation under combined Se-Cd treatment. Weighted gene co-expression network analysis suggested that 23 genes, such as inorganic phosphate transporter 1.3 and putative expansin-B2, may play key roles in regulating Se accumulation in C. violifolia treated with Cd. In conclusion, Cd promoted root Se uptake through enlarged root hair surface area and enhanced transporter gene expression. Meanwhile, Cd might promote Se volatilization via promoting key genes such as APK and APR , thus reducing Se accumulation in the shoots. This study provides a novel perspective and deepen our comprehension of Se-Cd interaction in plants. • Cd enhanced Se uptake in the roots yet reduced it in the shoots of C. violifolia . • Cd facilitated root hair formation, thereby augmenting root area and Se uptake. • PHT1.3 might be the key genes regulating Se uptake in the roots. • Organic Se increased by Cd may contribute to Se volatilization in the shoots.