高温与干旱胁迫对‘南林895杨’扦插苗生长和超微结构的影响

Effects of High Temperature and Drought Stresses on the Growth and Ultrastructure of Populus×euramericana‘Nanlin-895’Cutting Seedlings

【目的】研究‘南林895杨’扦插苗生长与细胞超微结构对高温、干旱及其复合胁迫的响应,探讨胁迫下叶片形态、生长与细胞超微结构损伤程度之间的关联机制,以期从形态和细胞学角度研究对不同胁迫响应机制的差异。【方法】‘南林895杨’扦插苗,设置不同的温度和水分梯度,比较高温、干旱单因素胁迫及复合胁迫下的扦插苗生长形态指标,并通过透射电镜观察超微结构变化。【结果】1)在高温、干旱单一胁迫和复合胁迫下,杨树地径、株高、生物量、叶分配指数均有不同程度下降,叶缘分裂程度、根茎比和根分配指数增大,复合胁迫对生长形态指标的影响大于单一胁迫;2)在高温、干旱单一和复合胁迫下,扦插苗叶片超微结构均受到不同程度的损伤,表现为叶绿体膨胀,膜系统紊乱,基粒片层扩张消融,嗜锇颗粒数量增多,淀粉颗粒减少以及重度胁迫下细胞排列松散。超微结构损伤程度与胁迫强度基本一致,重度高温胁迫比干旱胁迫对超微结构的影响更显著,复合胁迫对幼苗超微结构的影响大于单一胁迫。【结论】高温、干旱胁迫下叶片超微结构的损伤影响植物的光合作用和细胞内环境的稳定,正常的生理过程受到影响,并最终反映在植物生长形态变化上。‘南林895杨’扦插苗叶片超微结构的损伤程度与形态结构的变化基本一致,说明从形态和细胞学角度来揭示植物的胁迫响应机制是可行的。

【Objective】In this study,we investigated the response of the growth and cell ultrastructure of poplar cutting seedlings to high temperature,drought and their combined stresses,in order to explore the relationship between leaf morphology,growth and ultrastructure damage under stress and thereby reveal the differences of the response mechanism of poplar to different stresses from morphological and cytological perspectives.【Method】Cuttings of Populus×euramericana‘Nanlin-895’poplar were used as the experimental material.Different temperature and moisture gradients were set to study the growth and morphological indexes of poplar under single factor stress and combined stress of high temperature and drought,and the effects of different treatments on cell ultrastructure were investigated under TEM.【Result】1)Compared to the control,the basal diameter,seedling height,biomass and partitioning index of leaves decreased while leaf perimeter to area ratio,the ratio of root to shoot,partitioning indices of root increased under single or combined stress of high temperature and drought.The effects of combined stress on growth morphological index were greater than those of the single stress.2)Ultrastructure of leaves was damaged to different degrees under single or combined stress of high temperature and drought.Chloroplast swelled,and lamella structure expanded or even melt,osmiophilic granules content increased and starch granule content decreased,and even the arrangement of mesophyll cells was disorganized with damaged membrane structure under severe stress.The damage intensity of leaf ultrastructure was consistent with the stress level.Severe high temperature stress produced more obvious impact on ultrastructure than drought stress.The effects of combined stress on ultrastructure were greater than those of single stress.【Conclusion】Under high temperature and drought stress,the damage of ultrastructure of leaves affects the photosynthesis and the stability of the intracellular environment.Normal physiological processes are affected,and eventually results in the changes of seedling growth morphology.In this study,destruction of cell ultrastructure was consistent with the performances of growth morphology,which indicates the feasibility of revealing the response mechanism of plants to stress by cytology and morphology indicator analysis.