Toxicity Of Silver Nanoparticles On Spores Germination And Gametophytes Differentiation Of Ceratopteris Thalictroides

Silver nanoparticles(Ag NPs)is widely used in all walks of life because of its excellent antibacterial properties.In the process of production,transportation,application and recovery,Ag NPs is likely to be released from the consumer goods to aquatic environments.As a consequence,Ag NPs could cause some negative effects on aquatic plants.In the present study,we chose the aquatic plant,Ceratopteris thalictroides,as a model to investigate the effects of Ag NPs on on spore germination and gametophytes sex differentiation and growth.We also compared the toxicity of Ag NPs and Ag~+to clarify the toxicity mechanism of Ag NPs to C.thalictroides.The results showed that Ag NPs significantly affected the spore germination of C thalictroides,and the germination rate of C.thalictroides'spores significantly decreased with the increasing Ag NPs.The sex differentiation of the gametophyte of C.thalictroides was also significantly affected by Ag NPs.The proportion of hermaphrodites in the gametophytes decreased significantly with the increase of the concentration of Ag NPs,while the male gametophytes had no significant effect.The area of gametophytes was also significantly affected by Ag NPs,the area of hermaphrodites decreased significantly with the increasing concentration of Ag NPs,but the area of male gametophytes changed not significantly.By comparing the value of EC50,we found that the toxicity of Ag NPs to spore germination of C.thalictroides was slightly lower than that of Ag~+to spore germination of C.thalictroides,which was 49.2±1.2?g/L and34.9±0.7?g/L,respectively,indicating that the toxicity of Ag NPs and Ag~+was of the same order of magnitude.In this experiment,we compared with the control group by setting the filtrate of Ag NPs(remove nanoparticles)treatment group,Ag NPs treatment group which chelated Ag~+,found that the toxicity of Ag NPs to spore germination of C.thalictroides is not caused by the release of Ag~+,also is not caused by nanoparticles itself,we speculate that the toxicity of Ag NPs to spore germination of C.thalictroides and gametophyte growth is not only a simple contact stress,but at a deeper level of mechanism,such as Ag NPs may enter into C.thalictroides'spores,and its interaction,in turn,produce toxicity,to give enlightenment to us for the further research.