铝胁迫对龙眼叶和根细胞超微结构的影响

用扫描电镜、透射电镜、荧光显微镜研究铝胁迫对龙眼叶、根超微结构的影响。结果表明 ,铝胁迫造成龙眼叶片超微结构的破坏。其中最明显的变化是叶绿体的破坏 ,表现为叶绿体膜系统受损加重 ,基粒片层扭曲紊乱 ;其次是细胞壁的降解 ,细胞之间间隙变小 ,部分液泡膜破裂 ,液泡消失 ;线粒体膜系统受到破坏 ,嵴数量明显减少甚至消失。铝胁迫下龙眼根端膨大 ,根尖变粗变短 ,从外表皮到中柱出现不同程度的龟裂 ,且随铝浓度的提高 ,这种伤害程度不断加重 ;根伸长区细胞细胞壁发生降解 ,细胞间距变小 ;膜系统遭到破坏 ,核膜、线粒体膜破裂 ;细胞中淀粉粒明显减少 ,甚至消失 ;根尖分生组织细胞核变形 ,细胞核数量大大减少。

EFFECT OF ALUMINUM STRESS ON CELL ULTRA-STRUCTURE OF LEAF AND ROOT OF LONGAN(DIMOCARPUS LONGAN)

Using scanning microscope, clairvoyant microscope and fluorescent microscope, the responses of cell ultra-structure of Longan(Dimocarpus longan) leaves and roots to aluminum stress were studied. The results showed as follows: Aluminum stress caused damage on the cell ultra-structure of Longan leaves. The damage on chloroplast was most distinguished. Under aluminum stress, membrane system of chloroplast was damaged greatly, grana lamellae twisted and disordered. It was also found that the cytoplasm segregated from cell wall and the cell wall began to decompose, the clearance between cells became smaller, the vacuole lamellae broke, and the vacuole disappeared under aluminum stress. At the same time, the membrane system of mitochondrion was destroyed, and the number of cristae reduced and even disappeared. Under aluminum stress, the apices of root enlarged, the tip of root became shorter and thicker. The damage suffering from aluminum caused different degree crack on surface of root, and this kind of damage became more serious as the concentration of aluminum increased. Meanwhile, the cell wall of root enlongation part decomposed, the clearance between cells shorted, and the cell wall lost elasticity and became harder. The membrane system was destroyed, the cytoplasm segregated from the cell wall, and the lamellae of nucleolus and mitochondrion suffered disruption. The number of starch vacuoles reduced remarkably even disappeared, and the nucleolus of division part in root tip metamorphosed and the amount of nucleolus reduced greatly.