Comparative toxicity of nonylphenol, nonylphenol-4-ethoxylate and nonylphenol-10-ethoxylate to wheat seedlings (Triticum aestivum L.).

Nonylphenol polyethoxylates (NPEOs) are a group of surfactants that are widely used in industrial and household products and often detected in the environment. The metabolite of NPEOs, named nonylphenol (NP), has proven to be an endocrine disruptor, and its environmental behavior and eco-toxicity have been widely investigated in previous studies. However, to the best of our knowledge, insight into the toxicity differences of NP and NPEOs on important crops remains limited. Therefore, this study investigated the comparative toxicity of NP, nonylphenol-4-ethoxylate (NP4EO), and nonylphenol-10-ethoxylate (NP10EO) on wheat seedlings using hydroponic experiments. The results indicated that NP is most toxic to wheat followed by NP4EO, and NP10EO is the least toxic to wheat. The adverse effects of NP on wheat were observed for all the tested parameters including germination, shoot length, root length, chlorophyll, lipid peroxidation, and enzymatic activities. To gain insight into the molecular response, we analyzed the transcript abundance of SOD-Cu/Zn and CAT with NP, NP4EO, and NP10EO exposure using quantitative real-time PCR. The data revealed that both genes exhibited up- or down-regulated expression patterns that were consistent with the activities of the two enzymes. This result further conformed that NP is most toxic to wheat plants.