Fomesafen is a herbicide with long persistence in soil, causing damage to succeeding crops. Dichlormid is a widely used safener protecting maize from chloroacetanilide and thiocarbamate injury. We found that dichlormid treatment could restore the growth of wheat seedlings exposed to fomesafen stress. To explore its molecular mechanism, RNA-Seq was conducted to analysis transcript profiles between fomesafen and fomesafen+dichlormid treated wheat seedlings. The gene expression level was determined by qRT-PCR. Results showed that the up-regulated genes by dichlormid treatment were significantly enriched in pathways related to photosynthesis. The expression level of glutamyl-tRNA reductase (GTR), protoporphyrinogen IX oxidase (PPO, target of fomesafen), and magnesium chelatase (MAG) involved in chlorophyll biosynthesis was significantly up-regulated by dichlormid. And the expression level of genes in chlorophyll binding, energy biosynthesis, gibberellin biosynthesis and salicylic acid signal pathway was also validated to be significantly up-regulated by dichlormid. The detoxification enzyme activity of cytochrome P450 or glutathione S-transferase (GSTs), and their gene expression level was found to show no significant difference between fomesafen and fomesafen+dichlormid treatment. The antioxidant enzyme activity of peroxidase, superoxide, and the content malondialdehyde content was decreased by dichlormid, while the reduced glutathione content was increased by dichlormid significantly. The metabolism of fomesafen was further validated to be not influenced by dichlormid. These results suggested that dichlormid acted by increasing the expression of fomesafen target and photosynthesis related genes to alleviate fomesafen injury to wheat, but not accelerating fomesafen metabolism.

The widespread use of fluazifop-p-butyl (FPB) contributes to its presence in the environment. Considering the ecological risks of FPB residues in the environment, the anatase nanometer titanium dioxide (nano-TiO₂) mediated photocatalytic degradation of FPB was studied by smearing FPB and nano-TiO₂ together on a glass plane; illumination, trimethylsilane derivatization of photolysis products, high performance liquid chromatography (HPLC) quantitative analysis and gas chromatograph-mass spectrometer (GC-MS) identification were used. Results showed that the first order dynamic model could describe the photodegradation of FPB by nano-TiO₂ mediated, and the photodegradation and photosensitization rates were found to be positively correlated with the dose of nano-TiO₂ at lower dose ranges. It is noticeable that a strong photosensitization effect was exhibited on degradation of FPB, not only under high-pressure mercury lamps, but also simulated sunlight (xenon lamp light). Ultimately, twelve main photolytic products were reasonably speculated, whilst five photolysis pathways were proposed. These results together suggest that nano-TiO₂ can be used as an effective photosensitizer to accelerate FPB photolysis.