Overexpression of histone demethylase gene SlJMJ524 from tomato confers Cd tolerance by regulating metal transport-related protein genes and flavonoid content in Arabidopsis

Cadmium (Cd), as a heavy metal, not only negatively affects the development and yield of plants, but also threatens human health due to its accumulation in plants. Increasing evidences indicate that the JUMONJI-C DOMAIN-CONTAINING PROTEIN (JMJ) gene family plays a key role in regulating plant development and stress. Therefore, in this study, SlJMJ524, a 1254 bp gene encoding the jumonji C domain (417 amino acids), was highly expressed in tomato leaves and flowers. Interestingly, the transgenic plants exhibited sensitivity to Cd during post-germination stage but showed enhanced tolerance to the heavy metal during adult stage. Overexpression of SlJMJ524 increased the expression level of related proteins gene involved in heavy metal uptake while increasing Cd tolerance through the GSH-PC pathway. The higher transcription of genes related to flavonoid synthesis reflected higher accumulations of flavonoids in transgenic plants. Our study demonstrated that the ectopic expression of SlJMJ524 conferred the transgenic plants many traits for improving cadmium stress tolerance at different developmental stages. This study advances our collective understanding of the functional role of JMJs and can be used to improve the cadmium tolerance and breeding of crops and plants.