Salicylic Acid Binding Protein SABP2 Alleviates The Toxicological Effects Of Triclosan On Tobacco

As a broad-spectrum antibacterial agent,triclosan(TCS)is widely used in many fields such as medicine,daily chemicals and detergents due to its high antibacterial property.TCS is one of the most commonly detected organic pollutants in the sewage sludge.The sludge utilization for fertilizers on agricultural land would pose the risk of causing adverse effects on plant growth and yield by TCS.Salicylic acid(SA)plays a vital role in plant growth and development.Previous studies have shown that abiotic stress tolerance of plant could be enhanced by exogenous application of SA.However,specific functions of endogenous SA in plants’ defense responses to xenobiotics stress remains unclear.In this paper,tobacco(Nicotiana tabacum L.)was used as the research object to study the ecotoxicological effects of TCS on tobacco.On the basis of exogenous application of SA induced plant stress resistance,the mitigation effect of endogenous SA on the ecotoxicological effects of TCS in tobacco was studied.The molecular resistance mechanism of tobacco to TCS and the influence mechanism of endogenous SA on TCS resistance in tobacco were also studied at the transcriptome level.The results are as follows: 1.TCS at the concentration of 2.0 mg/L strongly inhibited the tobacco seed germination.TCS could suppress tobacco plants growth,and the chlorophyll content and photosynthetic rate decreased under TCS stress,while the content of reactive oxygen species(ROS)increased.2.The overexpression of LcSABP,clone from the leaves of Lycium chinense,markedly enhanced the SA accumulation in the transgenic tobacco under TCS stress.Transgenic tobacco presented higher chlorophyll content,photosynthesis rate,antioxidase activity,reduced glutathione content and lower malondialdehyde content,ROS accumulation and oxidized glutathione content in comparison with WT tobacco with TCS treatment.These results indicated that SABP2 had a positive regulatory role in plants response to TCS treatment via increasing the endogenous SA levels.3.By analyzing the results of transcriptome sequencing,it was found that the differentially expressed genes induced by TCS stress were mainly enriched in plant hormone signal transduction,plant MAPK signaling pathway and starch and sucrose metabolism.The differentially expressed genes between WT and transgenic tobacco under TCS stress were mainly concentrated in plant MAPK signaling pathway,biosynthesis of amino acids and plant hormone signal transduction.In summary,this study comprehensively explored the ecotoxicological effects of TCS on tobacco and the mitigation effect and mechanism of SABP2 on this toxicological effect.