Abstract: In order to exp lore the relationship between polyamines and pollen abortion of pear, the contents of different forms of putrescine ( Put) , spermidine ( Spd) and spermine ( Spm) were examined at different stages of pollen development in floral buds or anther of male sterile pear cultivar Niitaka (Pyrus pyrifolia Nakai) and fertile pear cultivar Housui. The results indicated that the variation range of contents of both free Put and Spd in Niitaka was small during bud development, whereas the variation of free Put and Spd content of
Housui showed a peak during uninucleate pollen stage to later uninucleate pollen stage. At the stage of pollen abortion ( from uninucleate pollen stage to later uninucleate pollen stage) , the free Put and Spd contentswere
3-5 times of Niitaka. Free Spm content in Niitaka was significantly lower than that of Housui. The contents of perchloric acid covalently soluble conjugated Put, Spd and Spm of Housuiwere gradually increased, but the contents of those in Niitaka showed a peak that did not appear in Housui during pollen abortion or ahead. Except developmentally mature anther, variations of perchloric acid covalently insoluble conjugated in two cultivars were similar. Total contents of different forms of Put, Spd and Spm did not have significant differences before pollen abortion, butwere significant lower in Niitaka than that of Housui after pollen abortion. The free Put, Spd and Spm were the p redominant forms in total contents in Housui, however, the p redominant forms in Niitaka were perchloric acid covalently soluble conjugated Put, Spd and Spm.

Key words: Pear, Pollen, Abortion, Polyamines