低温胁迫下甘蓝叶片细胞超微结构及叶肉细胞内Ca^(2+)的分布变化

Changes in ultra-structure and Ca^(2+) distribution in leaf cells of cabbage(Brassica oleracea L.) under low temperature stress

以结球甘蓝幼苗为试验材料,探讨低温胁迫下甘蓝幼苗超微结构及叶肉细胞内Ca2+水平的变化。结果显示:①5℃和2℃低温胁迫时甘蓝幼苗叶肉细胞质膜、液泡膜清晰,叶绿体、线粒体结构没有明显的变化,表明甘蓝幼苗对5℃、2℃低温逆境有一定的适应能力;-2℃低温处理的甘蓝幼苗叶肉细胞出现质膜内陷,大部分叶绿体双层膜结构破坏严重,基粒片层解体,线粒体膜结构受损,脊消失,表明甘蓝幼苗已受到冻害。②未经低温处理的甘蓝幼苗叶肉细胞中焦锑酸钙沉淀颗粒主要分布于液泡和细胞间隙中,细胞壁中也见少量沉淀,而细胞基质中则看不到焦锑酸钙沉淀;经-2℃24 h低温处理后,细胞间隙和液泡中的Ca2+开始释放到细胞质,细胞基质和细胞膜上焦锑酸钙沉淀增加,而液泡和细胞间隙中的焦锑酸钙沉淀减少;经-2℃48 h低温处理后液泡内和细胞间隙中的焦锑酸钙沉淀很少或消失,而细胞基质和细胞膜上则分布有较多的焦锑酸钙沉淀;经-2℃72 h低温处理后,细胞间隙内的焦锑酸钙沉淀极少,有的也紧贴在细胞外壁上,而细胞基质和细胞膜上则分布有非常多的焦锑酸钙沉淀,在核基质和液泡中也见到少量的焦锑酸钙沉淀,并且细胞发生质壁分离,超微结构遭到了显著破坏,表明Ca2+的区域性分布变化与植物抗寒性存在一定关系。

The changes of ultra-structure and Ca2＋ localization in the cabbage seedling leaf cells under chilling stress were investigated.The results showed that plasma membrane and tonoplast could be observed clearly,and chloroplasts and mitochondria did not display any significant changes at 5 ℃ or 2 ℃,which suggested that cabbage was adapted to chilling temperatures at 5 ℃ or 2 ℃.Under-2 ℃ cold stress,plasmalemma invagination appeared,leaf cell chloroplasts were destroyed,grana lamella were disorganized,membrane system of mitochondrion was totally destroyed,and cristae could not be found,which presented that cabbage young leaves were injured under-2 ℃ cold stress.When young cabbage grew at normal temperature,calcium antimonate which is the indicator for Ca2＋ localization mainly concentrated within the vacuoles and intercellular spaces.However,when treated at-2 ℃ for 24 h,calcium precipitates were found in cytoplasm and plasma membrane.When young cabbage was treated at-2 ℃ for 48 h,the deposits of Ca2＋ mainly concentrated within the cytoplasm and plasma membrane.When treated at-2 ℃ for 72 h,Ca2＋ was abundant within the cytoplasm,nucleus and plasma membrane;some cells appeared plasmolysis,and the ultrastructure of some cells was damaged severely.It can be seen that there are some relationships between the changes in Ca2＋ distribution within the cell and plant cold hardiness.