Photomodified fluoranthene exerts more harmful effects as compared to intact fluoranthene by inhibiting growth and photosynthetic processes in wheat

• Photomodified fluoranthene (P.FLT) is more toxic than intact fluoranthene.
• Both FLT and P.FLT significantly inhibit plant growth.
• P.FLT affected plant growth and photochemical reactions more than FLT.
• Antioxidant enzyme responses are similar in FLT and P.FLT treated plant.

Polycyclic aromatic hydrocarbons (PAHs) are toxic to plants. Exposure of PAHs to sunlight can result in the formation of photomodified PAHs, which are generally more toxic than the parent compounds. In the present study, biochemical and physiological effects of intact fluoranthene (FLT) and photomodified FLT (P.FLT) in wheat were investigated. Our results demonstrated that the treatment of FLT and P.FLT, inhibited germination, seedling growth and pigment content. However, inhibition observed on primary photochemistry and photosystem II heterogeneity was more prominent in P.FLT treated plants. Both FLT and P.FLT affected the levels of antioxidant enzymes such as POD, SOD, CAT and GR to similar extent. Greater inhibitory effects of P.FLT than FLT may be ascribed to its effects on growth parameters and photochemistry rather than on the activities of various antioxidant enzymes.