盐胁迫下欧李叶片叶绿体结构及功能与超微弱发光激发的关系

Relationship between Chloroplast Structure and Function and Ultraweak Luminescence Excitation of Cerasus humilis Leaves under Salt Stres

为探索叶绿体及其功能与超微弱发光(ultraweak luminescence,UWL)激发的关系,揭示UWL与植物生长生理的关系及植物中UWL产生来源,以欧李(Cerasus humilis)为材料,采用室内盆栽试验,设置不同浓度盐胁迫处理,研究盐胁迫下欧李叶片的叶绿体结构和功能(叶绿素代谢、光系统Ⅱ活性、光合性能和能量水平)及UWL的变化规律和相关性。结果表明,(1)盐胁迫降低了欧李叶片的UWL强度,且盐浓度越高,UWL强度下降程度越大;(2)盐胁迫破坏了欧李叶片叶绿体结构,并降低了其功能,具体表现为叶绿素合成主要前体物质(ALA、Mg-ProtoⅨ)含量显著降低,叶绿素降解酶叶绿素酶(Chlase)活性显著升高,导致叶绿素(Chla、Chlb、Car和Chla+b)含量显著降低,同时欧李叶片F_(v)/F_(m)、F_(v)/F_(o)、PIABS、RC/CS_(m)、φ_(E0)和Ψ_(E0)快速下降,光系统Ⅱ活性受到严重抑制,P_(n)、T_(r)、G_(s)下降,C_(i)同时升高,光合性能显著减弱,ATP含量和EC显著降低,导致能量水平整体下降;(3)欧李叶片UWL强度与其叶绿素代谢物质及叶绿素含量(ALA、Mg-ProtoⅨ、Chla、Chlb、Car和Chla+b)、光系统Ⅱ活性(F_(v)/F_(m)、F_(v)/F_(o)、PIABS、RC/CS_(m)、φ_(E0)、Ψ_(E0))、光合性能(P_(n)、T_(r)、G_(s))及能量水平(ATP、EC)等参数均呈显著或极显著性正相关关系;(4)盐浓度越高,胁迫时间越长,欧李叶片UWL强度与叶绿体功能各指标变化程度越大,且高浓度处理下的相关性整体高于低浓度处理。可见,在盐胁迫条件下,欧李叶片叶绿体结构被破坏,同时其功能受到损伤,活力下降,从而导致UWL强度降低;UWL强度与叶绿体及其功能关系密切,叶绿体可能是UWL的细胞器之一;UWL强度可以用来反映欧李叶片受盐胁迫伤害的程度。

In order to provide a theoretical basis for revealing the relationship between ultraweak luminescence(UWL)and plant growth physiology and the source of UWL production in plants,in this experiment,we used Cerasus humilis as the test material and conducted an indoor potted experiment with different 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 F_(v)/F_(m),F_(v)/F_(o),PI_(ABS),RC/CS_(m),φ_(E0) andΨ_(E0) of the leav-es of C.humilis decreased rapidly,and the activity of photosystemⅡwas 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),photosystemⅡactivity(F_(v)/F_(m),F_(v)/F_(o),PIABS,RC/CS_(m),φ_(E0) andΨ_(E0)),photosynthetic performance(P_(n),T_(r) and G_(s))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.