The E3 ubiquitin ligase gene SlRING1 is essential for plant tolerance to cadmium stress in Solanum lycopersicum.

• Cadmium (Cd) stress induced oxidative stress and reduced photosynthesis in tomato. • E3 ubiquitin ligase gene SlRING1 highly expressed in roots in response to Cd stress. • Silencing SlRING1 aggravated Cd phytotoxicity, H 2 O 2 content and oxidative damage. • SlRING1 deficiency reduced Cd-induced expression of CAT , DHAR , MDHAR , GSH , and PCS. • Suppression of SlRING1 expression increased Cd accumulation in shoots and roots. The E3 ubiquitin ligases participate in the degradation of plant proteins and play a regulatory role in stress response. However, the role of tomato E3 ubiquitin ligase genes in plant response to heavy metal stress remains elusive. Here, we identified 17 tomato E3 ubiquitin ligase genes using blast analysis of highly expressed E3 ubiquitin ligase genes of Arabidopsis thaliana. Through organ expression analysis, three E3 ubiquitin ligase genes with higher expression levels in roots were further screened out, and they were named Sl1 , SlRHE1, and SlRING1. Among these three genes, SlRING1 expression was the highest in response to cadmium (Cd) stress. Silencing SlRING1 significantly decreased chlorophyll content, Fv/Fm, photosynthetic rate, and biomass accumulation under Cd stress. The levels of H 2 O 2 , electrolyte leakage, and malondialdehyde significantly increased in SlRING1 –silenced plants under Cd stress compared with that in non-silenced tomato plants. Cd stress-induced increases in the transcript levels of antioxidant and detoxification genes such as CAT, DHAR, MDHAR, GSH, and PCS were compromised by SlRING1 silencing. Moreover, Cd accumulation in shoots and roots significantly increased in SlRING1 -silenced plants compared with non-silenced tomato plants. These findings suggest that SlRING1 plays a positive role in plant tolerance to Cd stress in tomato. [ABSTRACT FROM AUTHOR]