Abstract:

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.

Key words: Longan(Dimocarpus longan), Aluminum stress, Leaf, Root, Cell ultra-structure