Relationship between Chloroplast Structure and Function and Ultraweak Luminescence Excitation of Cerasus humilis Leaves under Salt Stress
In order to provide a theoretical basis for revealing the relationship between ultraweak lumines-cence(UWL)and plant growth physiology and the source of UWL production in plants,in this experi-ment,we used Cerasus humilis as the test material and conducted an indoor potted experiment with differ-ent concentrations of salt stress treatments to study the change rule and correlation of chloroplast structure and function(chlorophyll metabolism,photosystem activity,photosynthetic performance and energy lev-el)and UWL of C.humilis leaves.Results showed that,(1)salt stress reduced the UWL intensity of C.humilis leaves,and the higher the salt concentration,the greater the decrease in UWL strength.(2)Salt stress destroyed the chloroplast structure of C.humilis leaves and reduced its function.The decrease in chloroplast function included a significant decrease in the content of the main precursor substances for chlorophyll synthesis(ALA,Mg-ProtoⅨ),and the activity of chlorophyll-degrading enzyme chlorophyll enzyme(Chlase)significant increased,resulting in a significant decrease in chlorophyll contents(Chla,Chlb,Car and Chla+b).At the same time,the Fv/Fm,Fv/Fo,PIABD,RC/CSm,φE0 and ΨE0 of the leav-es of C.humilis decreased rapidly,and the activity of photosystem Ⅱ was severely inhibited,and further decreased on the Pn,Tr,and Gs,while Ci increased simultaneously,resulting in a significant decrease in photosynthetic performance.The significant decrease in ATP content and EC lead to an overall decrease in energy levels.(3)UWL intensity of C.humilis leaves and their chlorophyll synthesis precursors and chlo-rophyll contents(ALA,Mg-ProtoⅨ,Chla,Chlb,Car and Chla+b),photosystem Ⅱ activity(Fv/Fm,Fv/Fo,PIABS,RC/CSm,φE0 and ΨE0), photosynthetic performance(Pn,Tr and Gs)and energy level(ATP and EC)all showed significant or extremely significant positive correlations.(4)The higher the salt concentration,the longer the stress time,and the greater the degree of changes in the UWL intensity and chloroplast function indicators of C.humilis leaves,and the overall correlation under high-concentration salt treatment was higher than that under low-concentration salt treatment.In summary,under salt stress conditions,the chloroplast structure of C.humilis leaves was destroyed,while its function was damaged and its vitality decreased,resulting in a decrease in UWL intensity.The intensity of UWL was closely re-lated to chloroplasts and their functions,and chloroplasts might be one of the organelles of UWL.The UWL intensity could be used to reflect the degree of salt stress damage to the leaves of C.humilis.
salt stressCerasus humilischloroplast functionultraweak luminescence
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