Abstract: Biological characteristic and response to aluminum toxicity of cucumber (Cucumis sativa) root border cells have been studied. The experimental result indicated, during the sp rout p rocess of cucumber seed, the root border cells had very high viability. When the root length was 25 mm, the number of the root border cell reached its maximum ( about 5 480 ). The relative activity of PME ( Pectin methylesterase ) reached the maximum at 10 mm root length, then decreased gradually with the root elongating on. With the increasing concentration of Al³⁺ , root length and survival rate of border cells decreased. These results showed that aluminum toxicity had the obvious inhibition and harm to the growth of root and border cell. However, PME activity enhanced with the increasing concentration of Al³⁺ , showing PME was related to the stress of aluminum on plant. Simultaneously, the increase of PME activity under aluminum treatment condition caused demethylation of pectin in cucumber cell wall and increased Al³⁺ union position spots in the cell wall, thus
prevented much more aluminum from entering the cell and harming plant.

Key words: Cucumber, Border cell, PME, Root cap, Aluminum toxicity