Physiological Response And Signal Transduction Of Emmenopterys Henryi Oliv. Under High Light Stress

In this study,the seedlings of the Emmenopterys henryi Oliv with the same growth were divided into 4 groups,including growth under normal environment（CK）,exogenous 150μmol/L ABA spraying treatment（A）,distilled water spraying treatment（W）,and 20μmol/L Fluridone spraying treatment（F）.The last three groups were placed in a strong light environment of 10000 lx.The research content includes growth conditions and physiological characteristics,photosynthesis,and active oxygen metabolism.The purpose is to analyze the physiological response of Emmenopterys henryi Oliv to high light stress,and the protective mechanism of ABA.The main research results are as follows:1.Under high light stress,the increase rate of plant height,ground diameter,leaf length,leaf width and number of new leaves of Emmenopterys henryi Oliv slowed down,and the specific leaf weight decreased.Exogenous ABA can reduce the inhibition of high light on these morphological indicators,and the specific leaf weight does not decrease,but it has no obvious effect on the number of new leaves.2.High light stress caused a significant decrease in the total chlorophyll content and relative water content of the leaves of Emmenopterys henryi Oliv.Exogenous ABA can alleviate the degradation of chlorophyll under high light stress,and can relatively increase the relative water content of leaves;In terms of gas exchange parameters,Pn,Cond,and Tr of Emmenopterys henryi Oliv under strong light stress decreased,and Ci increased.Exogenous ABA can alleviate the decline of Pn,further reduce Cond and Tr,and finally Ci decreased;In terms of chlorophyll fluorescence parameters,high light stress leads to a decline in the heat dissipation capacity of Emmenopterys henryi Oliv,Y（NPQ）are lower than CK,Y（NO）rises,F_v/F_m,Y（Ⅱ）,F_v/F_o,r ETR（Ⅱ）are significantly reduced,ABA can relatively increase Y（NPQ）and decrease Y（NO）under light stress,effectively delaying the decline of F_v/F_m,Y（Ⅱ）,F_v/F_oand r ETR（Ⅱ）;In terms of photosynthetic enzymes,under high light stress,the activity of Ru BP carboxylase decreases,and the activity of PEPC increases.Exogenous ABA delays the decrease of Rubisco activity and further improves the activity of PEPC.3.Under high light stress,the accumulation of active oxygen in the leaves of Emmenopterys henryi Oliv increased,the content of H₂O₂and O.^2-increased significantly,the production of MDA and the relative conductivity increased,and the activities of SOD,POD,CAT and APX increased first and then decreased.The treatment of exogenous ABA improves the activity of POD and CAT of Emmenopterys henryi Oliv,alleviates the decrease of SOD and APX activity,effectively reduces the accumulation of H₂O₂and O.^2-,and reduces the damage to membrane lipids.