Spatial distribution and toxicity of cadmium in the joint presence of sulfur in rice seedling

• S supply can alleviate Cd toxicity.
• Cd accumulation in rice root was more than in shoot.
• Without S supply Cd distributed in the bottom of root while equally in shoot.
• S addition could facilitate Cd transfer to the top of shoot.
• S and Cd addition promoted the synthesis of thiol pool.

The spatial distribution and toxic effects of cadmium (Cd) in the joint presence of sulfur (S) in rice seedling remain almost unknown. Therefore, the indoor experiments test runs were performed to determine the accumulation and toxicity of Cd in presence of S for the first time. The results showed that S supply significantly reduced the Cd accumulation and toxicity due to the decrease of Cd availability. XRF observation results illustrated that in the single Cd treatments, Cd mainly distributed in the bottom of root, while equably existed in the shoot. Additionally, S addition could facilitate Cd transfer to the top of shoot and finally form the similar distribution trend for S and Cd, suggesting that S might increase the synthesis of thiol pool (such as PCs, GSH and NPT) and then chelate Cd, which further affected Cd translocation. Such observations have provided the useful information of potential ecotoxicological effects of Cd contamination in the environment.