Ca^(2+)预处理对热胁迫下辣椒叶肉细胞中Ca^(2+)-ATP酶活性的影响

Effect of Ca^(2+)Pretreatment on the Ca^(2+)-ATPase Activity in the Mesophyll Cells of Pepper Seedling Under Heat Stress

在常温下生长的辣椒 (CapsicumannuumL .)叶肉细胞中Ca2 + ATP酶主要分布于质膜、液泡膜上 ,叶绿体的基质和基粒片层上也有少量分布 ;在 4 0℃下热胁迫不同的时间 ,酶活性逐渐下降 ,直至叶绿体超微结构解体。同样条件下 ,经过Ca2 +预处理后 ,分布在上述细胞器膜或片层上的酶活性大大提高 ,表明Ca2 +预处理对该酶活性具有激活作用 ;Ca2 +预处理对热胁迫下的超微结构的完整性具有一定的保护作用 ,并且能使Ca2 + ATP酶在热胁迫下维持较高活性。结果表明 ,Ca2 +预处理增强辣椒幼苗的抗热性 ,可能与其稳定细胞膜、从而使Ca2 + ATP酶在热胁迫下保持较高活性有一定关系。

The changes in Ca 2+ ATPase subcellular distribution in calcium pretreated pepper leaves under heat stress at 40℃ were investigated. Under normal temperature, the Ca 2+ ATPase was localized mainly on the cytoplasmic side of the plasma membrane and the vacuole envelope, and a little Ca 2+ ATPase was observed in the grana and stroma thyakoid (PlateⅠ 1-3).After heat stress for some hours, the enzyme activity declined and the ultrastructure of chloroplasts was damaged by heat stress (PlateⅠ 4-6). Under the same conditions, the enzyme activity localized at the above organelles in calcium treated pepper leaves increased markedly, indicating the improvement of Ca 2+ ATPase activity by calcium pretreatment (PlateⅡ 9-16). In addition, calcium pretreatment was able to maintain the integrity of the cell ultrastructure and a higher level of enzyme activity of the pepper mesophyll cells under heat stress. These results suggested that the improvement of thermotolerance in pepper seedlings caused by calcium pretreatment might result from its contribution to maintain the higher ATPase activity under heat stress.