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以‘新泰密刺’黄瓜为试材,采用焦锑酸钙沉淀的电镜细胞化学方法,研究不同浓度NO3-胁迫下黄瓜幼苗根系分生区细胞内Ca2+的分布变化,以期为探讨不同浓度NO3-胁迫下细胞内Ca2+行为特征与黄瓜对NO3-适应性之间的关系。结果表明,对照生长条件下(14mmol.L-1NO3-),黄瓜根系分生区细胞内Ca2+主要出现在细胞膜和小液泡内,线粒体、细胞质和细胞核及核仁内也有少量的较小颗粒钙沉淀。而其它浓度NO3-胁迫下,其根系分生区细胞内Ca2+定位分布变化明显。在56和140mmol.L-1NO3-浓度下,Ca2+有向细胞基质分布的趋势,其细胞间隙、细胞质和线粒体中亦出现大量钙沉淀颗粒。且不同处理浓度下,线粒体和小液泡数量及结构变化较大。而当NO3-浓度达182mmol.L-1时,根系分生区各细胞器内钙沉淀颗粒明显减少,此时Ca2+的变化是各细胞器及膜系统遭严重破坏的结果。综上可知,黄瓜幼苗可通过根系分生区液泡内Ca2+向细胞基质分布变化,来增加对高浓度NO3-胁迫的抗性。
In this study, we investigated the distribution of intracellular Ca2 + in root zone of cucumber seedling under NO3- stress by using the electron microscopy cytochemistry method of ’Xintailingci’ cucumber with calcium pyroantimonate precipitation, in order to investigate the effects of different concentrations of NO3 Relationship between Intracellular Ca2 + Behaviors and NO3 - Adaptation in Cucumber. The results showed that under the control of growth conditions (14mmol.L-1NO3-), the intracellular Ca2 + in cucumber root zone mainly appeared in the cell membrane and small vacuoles, and there were also a few small granular calcium precipitates in mitochondria, cytoplasm, nucleus and nucleolus . Under the condition of NO3-stress, the distribution of intracellular Ca2 + in root zone of root exudates changed obviously. At concentrations of 56 and 140 mmol.L-1NO3-, Ca2 + showed a tendency of distribution toward the matrix of the cells, and a large amount of Ca2 + precipitates appeared in the interstitial space, cytoplasm and mitochondria. Under the different treatment concentrations, the quantity and structure of mitochondria and small vacuoles changed greatly. When the concentration of NO3- reached 182mmol.L-1, the amount of Ca2 + in the organelles of root zone was significantly decreased. At this time, the change of Ca2 + was the result of severe destruction of organelles and membrane systems. In summary, cucumber seedlings can increase the concentration of NO3-stress resistance by changing the distribution of Ca2 + in the meristematic zone of the root system to the cell matrix.