Abstract: With the materials of the fruit cultivar Pyrus bretschneideri at different development stages，key enzyme POD types of lignin metabolic pathway，namely the relationships of GSH-PX，APX and PPOD activity and lignin metabolic of stone cell，were investigated by the methods of histochemical localization，POD activity and isoenzymes spectrums. POD types of the key enzyme involved in lignin metabolic pathway were analyzed during the stone cell development. The results were as following：（1）During the fruit development of Pyrus bretschneideri，POD located in the cell wall of stone cells as well as the neighboring regions was involved in the procedure of lignin deposition in the cell wall of stone cells.（2）In 15–23 days post anthesis，POD isozyme spectrums were mainly divided into three groups of PODⅠ，PODⅡand PODⅢ，of which the Rf values were 0.13–0.23，0.44 and 0.63–0.96，respectively.（3）PPOD was the main type of the key enzyme POD in lignin metabolic pathway，in which it was involved in the polymerization of lignin and promoted the development of stone cells during fruit development of Pyrus bretschneideri.

Key words: pear, Pyrus bretschneideri, GSH-PX, PPOD, APX, stone cell, lignin