Mechanism and stability of low cadmium accumulation in grafted soybeans induced by rootstocks

Background Grafting can effectively reduce cadmium (Cd) accumulation in Solanaceae fruits. However, few studies have investigated the mechanisms and stability involved, making it difficult to apply grafting to a large area of Cd-contaminated farmland. Methods Soybeans were grafted with low Cd accumulation variety rootstocks and varieties with high Cd accumulation as scions. High-throughput sequencing and q-PCR were used to explore the mechanism and stability of rootstock-induced low Cd accumulation in scions. Results Grafting using low Cd accumulated varieties as rootstocks reduced the Cd content in the grafted soybeans by 50–70% and did not affect the yield and quality of soybeans. In addition, most of the differentially expressed genes (DEGs) induced by grafting were enriched in S-related pathways. In the grafted soybean with the best effect of Cd inhibition, compared with the control, the Cd content in the offspring decreased by more than 50%. Further, q-PCR showed that there was no significant difference in the expression patterns of the differential genes between scion leaves and offspring leaves. Conclusion Rootstock with low Cd accumulation affects the transfer of Cd from the roots to the shoots, which is related to the downregulated expression of S-containing compounds that can be stably maintained in offspring.