Response Research Of Reactive Oxygen Species In Soybean Plants To Bisphenol A Stress

Bisphenol A?BPA?is an important raw material for the synthesis of industrial products such as epoxy resins,polycarbonates and polysulfone resins,and its use is still expanding.BPA has been widely existed in the global environment and become a new environmental pollutant,so the potential harm of BPA has become a global environmental risk and has been widely concerned.BPA can disrupt organism's endocrine system and affect its growth and development at a lethal dose.To date,reports about the effects of BPA on living systems are mostly found in animals and humans,and rare in plants.As for the response of plants to BPA stress pathways,it is worth paying attention.Reactive oxygen species?ROS?are cellular biochemical reaction systems that plants evolve to adapt to changes in the earth's atmosphere.ROS stress metabolism is one of the common responses of plants to adversity,which may be involved in the control and regulation of various life processes and stress responses.It is worth noting that whether plant ROS play an active protective role under the environmental-dose BPA pollution stress.Therefore,in this study,Glycine max.L,a typical environmental toxicological plant,recommended by the US Environmental Protection Agency?US.EPA?,was used to study the response of ROS metabolism in soybean plants to BPA exposure using laser scanning confocal microscopy.The relationships between ROS levels and BPA content in soybean plants were analyzed.The main three results are shown below:?1?Compared with the control,with the prolonged exposure time of low-dose(?3.00mg·L^-1)BPA,the stress chain reaction of ROS in soybean roots at the seedling stage occurred and gradually accumulated,but did not cause lipid peroxidation.In addition,ROS levels and residual BPA content in soybean roots showed inverse relationship,which means the BPA content decreased with the increase of ROS levels to the 9th hour,ROS responded to BPA stress and oxidized BPA in roots to reduce BPA content and injury.Exposure to high doses(?6.00 mg·L^-1)of BPA caused the ROS stress response in soybean seedling roots to intensify and over-accumulate as the BPA exposure time continued,leading to gradual over-oxidation of membrane lipids.At the same time,residual BPA content in soybean seedling roots gradually increased with the extension of exposure time.Under the same dose of BPA exposure,the above indices in soybean seedling leaves were similar to those in roots,but lower than those in roots and showed differences later.After the release of BPA,all the above indicators in soybean seedling have been reduced.The higher the dose of BPA exposure,the lower the recovery of the above indices after the release of BPA exposure.?2?Compared with the control,the elicited changes of ROS in soybean roots and leaves at flowering and podding stage were similar to the seedling stage.After high-doses(?6.00mg·L^-1)BPA exposure,membrane lipid peroxidation occurred gradually but later than the seedling stage,at the same time node,the membrane lipid peroxidation degree at the flowering and podding stage was lower than that at the seedling stage,the physiological structure of soybean plants at the flowering and podding stage gradually stabilized and their stress resistance increased.In addition,the relationship between ROS levels and residual BPA content in soybean plants at flowering and podding stage were more significant than that at the seedling stage,this corresponds to the fact that the BPA content in soybean plants at flowering and podding stage is lower than that of the seedling stage.After the release of BPA,the above indices at flowering and podding stage were reduced,and the reduce degree was higher than the seedling stage.?3?Compared with the exposed group without diphenyl ether iodine treatment,ROS stress response in soybean plants at two growth stages were inhibited.At the same time node,the ROS levels in exposed groups after diphenyl ether iodine treatment were lower,and the residual BPA content in soybean plants was higher.The relationship between the ROS levels and residual BPA content in soybean plants at two growth stages were more subtle,and the efficiency of ROS in oxidizing BPA was weakened.In summary,ROS in soybean plants can decrease BPA content to reduce BPA damage.ROS in soybean plants response to exogenous BPA stress varies according to different growth stages and organs of plant,ROS levels showed the following rules:roots at the flowering and podding stage>roots at the seedling stage>leaves at the flowering and podding stage>leaves at the seedling stage.Residual BPA content in soybean plants showed the following rules:roots at the seedling stage>roots at the flowering and podding stage>leaves at the seedling stage>leaves at the flowering and podding stage.Therefore,the ROS stress protection function produced by the plant itself at a specific dose can not be ignored when evaluating the environmental risk of BPA.