The heavy metal cadmium (Cd) can migrate and accumulate in soil-plant system and threaten food safety and the health of people. Therefore, it is thus important to develop pollution control techniques for Cd-contaminated soils and to explore the mechanism affecting cadmium absorption, transportation and accumulation in crops. 

Prof. TAI Peidong, a senior researcher from the Institute of Applied Ecology (IAE) of the Chinese Academy of Sciences (CAS), has led a series of research investigating the mechanism that regulates long-distance translocation of cadmium from root to shoot by means of grafting. 

His team found that compared with un-grafted controls, grafting led to a prominent reduction of cadmium content (-60%~80%) in the fruits of eggplants (S. melongena) grafted onto Torubamu (Solanum torvum) as a rootstock, without affecting crop yield and quality.  

The researchers also found that grafting reduced cadmium accumulation in soybean (Glycine max). More importantly, the "low Cd traits can be maintained over two generations," the researchers announced. 

By performing DNA methylation and high-throughput sequencing analyses, the researchers found that most of the grafting-induced Differentially Expressed Genes were enriched in sulfur-related metabolism pathways (e.g., glutathione, cysteine and methionine metabolism).  

They further confirmed that sulfhydryl compounds and sulfur-containing compounds involved in the regulation of the translocation and accumulation of cadmium in crops, and that grafting could impact the synthesis and metabolism of these sulfur-related compounds by affecting miRNAs and DNA methylation, and led to low cadmium traits (phenotype) in scions of grafted crops and in their offspring. 

These findings comprehensively explained the mechanisms regulating cadmium transportation and accumulation in crops, indicating that grafting can be used as agronomic measures in heavy metal contaminated farmland to reduce cadmium content in crop products. 

These studies were funded by the National Natural Science Foundation of China and the National Key R&D Program of the Ministry of Science and Technology.