The Response Mechanism Of Antioxidant System To UV-B Radiation In Glycyrrhiza Uralensis Fisch Leaves

In order to investigate the response mechanism of UV-B radiation in leaves of Glycyrrhiza uralensis Fisch,we used ROS fluorescence detection under the conditions of artificial simulated treatment(10000 lx light intensity + UV-B radiation dose of 2.4 uw/cm2)using G.uralensis seedlings as material.Needle location techniques,modern biochemical analysis techniques,transcriptome and metabolome analysis techniques were used to study the G.uralensis leaves with different UV-B radiation treatment time(2 h,6 h,12 h,24 h,48 h,96 h),and the results showed that:1.The increase of UV-B radiation resulted in the increase of intracellular ROS content in leaves of G.uralensis.The increasing trend depends on the change of treatment time.The oxidative damage caused by the accumulation of ROS on the biofilm system of G.uralensis leaf cells also increased gradually.When UV-B radiation intensity is less than 10.368 kJ/m2,UV-B radiation has less damage to the cell membrane of G.uralensis leaves.In this case,the G.uralensis leaves cells can clear away the UV-B radiation generated and accumulated ROS through their own clearance.Maintains the balance of intracellular oxidation.When the radiation intensity is higher than 10.368 kJ/m2,the ROS balance in the cells of G.uralensis leaves have been broken.The degree of oxidative damage caused by UV-B radiation on the biofilm system of G.uralensis leaves increases with the increase of radiation intensity,which affects the physiological and biochemical changes of cells.The process even led to cell death.2.The response of antioxidant system of G.uralensis leaves to low-dose UV-B radiation is different due to different treatment time.The activity of various antioxidant enzymes in cells varies with the time of UV-B radiation,and the activities of SOD and GPX with radiation The increase of time showed a trend of increasing first and then decreasing.The activities of SOD and GPX in the leaves of G.uralensis treated with UV-B radiation were higher than those in the control group.The CAT activity increased first and then decreased with the increase of UV-B radiation time.When the intensity of UV-B radiation was greater than 10.368 kJ/m2,the CAT activity in leaves of G.uralensis was inhibited;the activities of POD and GR increased with the increase of UV-B radiation treatment time.3.The contents of flavonoids in leaves of G.uralensis with UV-B radiation treatment time increased,showing the trend of increasing first and then decreasing.There were 36 kinds of flavonoids components detected in the leaves of G.uralensis treated with UV-B radiation at different times,such as apigenin.,naringenin and so on.Due to different functional groups of each component,the response mechanism to UV-B radiation is also different,so the variation trend is different with the increase of UV-B radiation treatment time;the content of polyphenols in the cells of G.uralensis leaves increases with UV-B radiation treatment time,presenting The trend of increasing and then decreasing and then increasing,22 kinds of polyphenols such as 4-Coumaric acid,Caffeic acid and Chlorogenic acid were detected in the leaves of G.uralensis with different UV-B radiation treatment times.The increase in radiation treatment time of-B shows different trends.4.UV-B radiation treatment at different times,the G.uralensis leaf cells within the gene response pattern is different,according to the differential gene expression patterns,the test components can be 3 categories,including:CK and 2 h;6 h and 12 h;24 h,48 h and 96 h.In addition,UV-B radiation stimulated the up-regulation of SOD,POD,GPX,GR,PAL,C4H,CHS,FLS,and PPO in response to UV-B radiation treatment.Expression,in which high-intensity UV-B radiation on the promotion of POD,GR is more obvious,but CAT is different,low-intensity UV-B radiation can stimulate CAT expression,high-intensity UV-B radiation inhibits CAT expression.5.UV-B radiation enhanced the interaction between UVR8,CAM,ABA,and ROS signaling substances in the cells of G.uralensis.These signals also stimulated the increase of intracellular antioxidant enzyme activity and the enhancement of the activities of key antioxidant enzyme synthesis enzymes.ETH-mediated apoptotic mechanism activation activates the synergistic action of the aforementioned pathways to promote the enhanced defense response of G.uralensis to UV-B radiation.