为探索硅(Si)增强微咸水长期灌溉下库拉索芦荟(Aloe vera L.)耐盐性的机制,研究了盐(NaCl 100 mmol·L-1)胁迫下加Si(2.0 mmol·L-1)处理30 d对库拉索芦荟叶同化组织细胞中矿质离子分布、叶绿体超微结构和腺苷三磷酸(ATP)酶活性的影响.X-射线能谱微域分析结果表明,盐胁迫下加Si,芦荟叶同化组织细胞中钠离子(Na+)和氯离子(Cl-)相对含量显著下降,伴随着钾离子(K+)相对含量显著升高、钾钠比(K+/Na+)显著增大.同时,加Si利于保持芦荟叶绿体正常形态,保护光合层片精细结构,显著缓解盐胁迫对其光合细胞器的伤害.利用电镜-细胞化学技术首次表明,提高浇灌溶液中可溶性Si含量水平,明显增强盐胁迫下芦荟叶同化组织细胞中胞间连丝、质膜和液泡膜ATP酶活性.外源Si增强盐胁迫下芦荟叶同化组织细胞中ATP酶活性是其改善叶同化组织细胞中的离子分布、缓解芦荟盐胁迫伤害效应的重要机制.%To explore the mechanism of added silicon (Si) enhancing salt tolerance of A. Vera L.under long-term irrigation with brackish water, the effects of exogenous Si on mineral ion distribution, chloroplast ultrastructure and adenosine triphosphatase (ATPase) activity in leaf chlorenchymatous cells of A. Vera L. NaCl-induced salt stress for 30 d were investigated. Results by energy dispersive X-ray microanalysis showed that the relative content of sodium ion (Na+) and chloride ion (Cl-) significantly decreased, coupling with a significant increase of the relative content of potassium ion (K+ ) and the K+/Na+ ratio, in leaf chlorenchymatous cells of aloe under 100 mmol·L-1 NaCl stress with added Si 2.0 mmol·L-1, so did in other three leaf tissues. Meanwhile,added Si was favourable to maintain the morphology and structure of aloe chloroplast and to protect the integrity of thylakoid structure, illustrating that exogenous soluble Si alleviated injury of salt stress to photosynthetic organelle of aloe. Further study with electron-microscopy (EM)-cytochemical technique showed that ATPase activity, indicated by the status of cerium phosphate (CePO4)precipitated products, in plasmodesma, plastma membrane and tonoplast of aloe leaf chlorenchymatous cells was evidently increased under salt stress with added Si. Enhancing ATPase activity is an important mechanism for exogenous Si to improve salt ion microdistribution, and to alleviate the effects of salt injury on aloe.
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