Tissue-specific Metabolic Response Of Acanthopanax Senticosus (Rupr.Maxim.) Harms Leaves To UV-B Radiation

Acanthopanax senticosus(Rupr.Maxim.)Harms is a genus of Acanthopanax,which is a traditional Chinese medicinal material with a variety of pharmacological effects.With the current changes in environmental conditions worldwide,in recent years,the surface-received UV-B radiation is increasing year by year.As one of the important reasons for inducing plant light stress,ultraviolet radiation can activate the plant defense system and complete the metabolic response,thus affecting the physiological metabolism and medicinal activity of A.senticosus.The leaves as an important organ for plants to receive and respond to UV-B radiation,the current research on the tissue-specific response of different leaf positions to UV-B radiation is not comprehensive.Therefore,this study systematically studied the photosynthesis,antioxidant enzyme activity,main medicinal active ingredients of UV-B radiation on different leaf positions of A.senticosus by applying different intensity of UV-B radiation to A.senticosus.The effects of targeting phenolic compounds,etc.,revealed the tissue-specific metabolic response of A.senticosus leaves to UV-B radiation,and the following conclusions were obtained:(1)UV-B radiation caused different degrees of damage to the leaves of A.senticosus.With the increase of UV-B radiation intensity,the plant height and new leaf area growth of A.senticosus were inhibited,and the A.senticosus was reduced.Photosynthetic activity,and the upper leaves were most affected by UV-B radiation.With the increase of UV-B radiation intensity,the activities of ascorbate peroxidase(APX),catalase(CAT)and peroxidase(POD)in the leaves of A.senticosus increased first and then decreased,moderate treatment>severe treatment>control group.CAT and superoxide dismutase(SOD)activities were significantly affected by leaf position factors,while there were no significant differences in APX and POD activities at different leaf positions.(2)After UV-B irradiation,the saponins of A.senticosus showed strong tissue specificity,and under moderate stress,the content of oleanolic acid in the leaves was significantly increased,and the isoxazinidine and gold in the upper and lower leaves.The content of candidin;the content of isoxazinidine and hyperoside in all leaves increased under severe stress,but the content of oleanolic acid decreased.Through the analysis of principal component Q value,the comprehensive scores of active components of all leaves under severe stress were significantly improved.The five medicinal active ingredients in A.senticosus were extremely significant(p<0.01)affected by single factors of leaf position or treatment and leaf position ×treatment complex factors.(3)A total of 14 phenolic compounds in the leaves of A.senticosus were determined.After UV-B irradiation,the accumulation of phenolic compounds in the upper leaves increased,and increased with the leaf position.After moderate stress,the accumulation of C6C1 compounds in all leaves showed an upward trend;UV-After B stress,the accumulation of C6C3 compound decreased as a whole.After UV-B stress,the accumulation of flavonoids(C6C3C6)was generally increased,and kaempferol was the most obvious.(4)Correlation analysis showed that there was a significant negative correlation between the active components of A.senticosus and isoflavone and some of the C6C3 phenolic compounds(p<0.05).C6C1 compound syringic acid,salicylic acid,C6C3C6 compound kaempferol,rutin and antioxidant enzymes APX,CAT and POD were positively correlated.It is indicated that these compounds may be associated with an increase in the antioxidant capacity of A.senticosus.