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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. [ABSTRACT FROM AUTHOR]

Aims: Grafting is an effective strategy to reduce the accumulation of cadmium (Cd) from the soil to the aerial plant parts. However, few studies have investigated the mechanisms involved. Methods: DNA methylation and high-throughput sequencing were used to explore the mechanism of the Cd reduction in grafted eggplants (Solanum melongena) on Torubamu (Solanum torvum) as a rootstock. Results: Compared to un-grafted eggplants, grafting significantly reduced Cd accumulation in the leaves and fruits by 65.21% and 81.48%, respectively, of grafted eggplants cultivated in 3 mg kg−1 Cd-contaminated soil. In addition, the total methylation levels of CG, CHG, and CHH were reduced in grafted eggplants, leading to lower total cytosine methylation level than in un-grafted eggplants. The most significant change occurred in CHH methylation in the repeat elements. Furthermore, there were 55 hypomethylated and 23 hypermethylated genes in the leaves of grafted eggplants, most of which were involved in S metabolism, correlating with a decrease in S compounds. Conclusion: Grafting using S. torvum as a rootstock could impact S compounds regulation by altering DNA methylation levels, and thereby, reducing Cd accumulation in scions of grafted eggplants. [ABSTRACT FROM AUTHOR]

Aims: This study aims to understand the mechanism by which grafting tomato (Solanum lycopersicum) onto Torubamu (Solanum melongena) reduces cadmium (Cd) accumulation in tomato. Methods: Tomato plants were grafted onto Torubamu rootstocks, and both the un-grafted and grafted tomato plants were grown in the control soil and soil that contained 2.0 or 5.0 mg•kg−1 Cd for 30 d. Results: Grafting onto Torubamu rootstock markedly reduced the accumulation of both Cd and total sulfur in the leaves of tomato plants to 4.1–11.7% and 25.0–36.7% of the values in the un-grafted tomato plants, respectively. Moreover, the expression of miR166a and miR395b markedly increased in tomato scions. Tobacco dual-luciferase (LUC) assays and Agrobacterium-mediated tomato genetic transformation verified that miR166a and miR395b targeted Phavoluta (PHV), Revolute (REV), Class III Homeodomain Leucine Zipper (HD-ZIP), Sulfate transporter 2;1 (SULTR2;1), ATP sulfurylase (APS) (APS1/3), and High-affinity sulfate transporter (HAST) genes, which are directly or indirectly responsible for sulfate transport. Conclusions: Based on the correlations between the Cd and sulfur accumulation in the tomato scions (r2 = 0.91) and in the miR166a/395b-transformed tomato scions (r2 = 0.96–0.98) grown in the soil with 2.0 mg•kg−1 Cd, we conclude that tomato grafting onto Torubamu rootstock can reduce Cd accumulation because of the sulfate transport regulatory ability of miR166a and miR395b. Understanding this mechanism can be of great benefit for Cd tolerance breeding. [ABSTRACT FROM AUTHOR]