SlJMJ12 overexpression confers improved cadmium tolerance in Arabidopsis and tomato.

Cadmium (Cd) is a toxic heavy metal threatening ecosystems and crop production. The functions of histone demethylases in plant Cd tolerance remain poorly understood. We functionally characterized the tomato histone demethylase SlJMJ12 using Arabidopsis and tomato. Cd rapidly induces leaf-expressed SlJMJ12, with peak expression at 3 h post-treatment. Compared with the wild type, SlJMJ12 loss-of-function mutants show Cd sensitivity in both Arabidopsis and tomato, with reduced biomass, higher plant Cd and ROS levels, and decreased antioxidant enzyme activities, whereas overexpression improves Cd resistance. Mechanistically, SlJMJ12 modulates genes governing metal uptake, translocation and chelation (AtZIP1, AtABCC1, AtNRAMP4, SlIRT1, SlNRAMP3, SlGSH1). Y2H screening further identified Cd-inducible SlKLCR1-Like as its putative interacting partner, which requires further functional verification. In summary, this study demonstrates the positive regulatory role of SlJMJ12 in plant Cd tolerance. These results enrich the regulatory mechanism underlying plant heavy metal tolerance and provide a valuable gene resource for breeding Cd-tolerant crops.