Abstract: Malus zumi is an important greening tree and is also an important rootstock of apple, with strong salt tolerance. In this study, the matural Malus zumi was used as the test material, which was rejuvenated by tissue culture to explore the physiological and biochemical changes and histological structure of Malus zumi during rejuvenation. The healthy leaves of the zero generation and the rejuvenated generation of 1, 3, 5 and 7 generations were taken respectively. The soluble sugar content and soluble protein content were determined. The histological structure was analysed with stem and leaves. The results showed that the content of soluble sugar in leaves decreased with the continuous subcultures, and these indexes in 5th rejuvenated generation were significantly different from those in the zero generation. However, there was no significant difference in the content of soluble protein between the 0 generation and the 1, 3, 5 generation. Until the 7th generation, there was a significant difference to the zero generation of soluble protein content. With the continuous subcultures, the palisade tissue gradually decreased, the upper and lower epidermal cells increased and cell wall became thinner. The xylem of the stem gradually decreased. From this experiment we concluded that tissue culture can rejuvenate Malus zumi, and the continuous subcultures are beneficial to rejuvenation.

Key words: Malus zumi, rejuvenation, histological structure, physiological biochemistry