Effects Of Chiral Herbicide Quizalofop-Ethyl On Physiological Changes And Gene Expression In Microcystis Aeruginosa

The ecological environment and human health problems caused by the massive use of chiral herbicides are getting more and more attention.Quizalofop-p-Ethyl is an often applied phenoxy herbicide,it can impact the propagate on aquatic organism.Cyanobacterial blooms pose serious problems to the human health and the aquatic environment.As the foundation of aquatic ecological system,cyanobacteria are considered to be effective indicators of ecological risk of various toxicants.Microcystis aeruginosa(M.aeruginosa)was selected as experimental objects to study the toxic mechanismof Quizalofop-p-Ethyl and Quizalofop-Ethyl,including physiological and m RNA abundance levels.Under the laboratory setting concentration,acute toxicity is positively correlated with concentration and exposure time of Quizalofop-p-Ethyl and Quizalofop-Ethyl.Quizalofop-Ethyl showed earlier toxicty.Low concentration of Quizalofop-Ethyl stimulated the growth of M.aeruginosa that may promote the outbreak of "water bloom".Quizalofop-Ethyl and Quizalofop-p-Ethyl both inhibited the content of chlorophyll a and protein.Quizalofop-p-Ethyl was more toxic than Quizalofop-Ethyl.Quizalofop-p-Ethyl and Quizalofop-Ethyl disturbed electron transport chain,decreased photosynthetic content,and reduced the transcript abundance of psa B using the real-time PCR.Quizalofop-Ethyl also showed a stress response to maintain photosynthesis during the first generation of M.aeruginosa,and stimulated the expression of psb D1.Both herbicides stimulated the content of MDA and the activities of SOD and CAT,suggesting that there was some oxidative damage.The release of MC-LR was affected by Quizalofop-p-Ethyl and Quizalofop-Ethyl.1,5 mg/L Quizalofop-p-Ethyl was more potent in stimulating MC-LR than Quizalofop-Ethyl.Quizalofop-p-Ethyl and Quizalofop-Ethyl also affected the transcript abundance of mcy H.The mechanism of enantioselective toxicity by Quizalofop-p-Ethyl and Quizalofop-Ethyl was investigated in our study.It is to offer the theoretical foundation for the chiral pesticide application and production.These studies are also important in ecological risk assessment.