Effects Of Endogenous Polyamine Metabolism On Flowering,Fruiting And Dormancy In Pear

'Akiba' pear(Pyrus serotina 'Akiba'),'Kousui' pear(Pyrus serotina 'Kousui'),'Housui'pear(Pyrus serotina 'Housui')and 'Chuan Li'(Pyrus pashia D.Don)were used as experimental materials in this article.Changes in the type and contents of free and bound polyamine in different floral organs before and after selt-pollination and cross-pollination were investigated.The effects of different concentrations and different kinds of gibberellin on the fruit growth in'Housui' pear were compared,combined with the forms and levels of endogenous polyamines in fruits after treatment analyzed.In addition,impacts of root on the dormancy process of 'Chuan Li' buds and its relationship with endogenous polyamine metabolism were discussed.The main results were as follows:1.The free polyamines were the predominant forms in pollen of the self-compatible cultivar'Akiba',while the bound polyamines were in majority in the self-incompatible cultivar 'Kousui'pollen.It indicated that the forms of polyamines were related to the activity and fertility of pollen.2.Compared with the changes of Put,Spd and Spm content,the tendency of(Spd+Spm)/Put was more consistent with the compatibility,which meant that the ratio of(Spd+Spm)/Put was closely related to the successful accomplishment of pollination and fertilization in sand pears.3.Comparing the variation tendency of bound Spd and the final content of the free Put in styles of 'Akiba' and 'Kousui'pear after self-and cross-pollination,combined with self-compatibility of themselves.It is considered that free Put and bound Spd were the most important polyamines which influenced the self-compatibility.4.The contents of free and bound Put,Spd and Spm in 'Housui' pear changed with the development of fruit.Among them,the variation tendency of Put was most consistent with the process of cell division and expansion.5.Exogenous gibberellin could affect the division and expansion of 'Housui' fruit cell by adjusting the content of endogenous free Put.The promoting effect of GA3 on the biosynthesis of free Put was better than that of GA4+7 during cell division phase,while in the cell expansion phase,GA4+7 could better promote the increase of free Put content.6.The germination rate of CK and treatment was significantly different in the whole period,and the bud dormancy release date of excising treatment was nearly 2 months earlier than CK.It illustrated that the root system made an important impact on regulating the dormancy process of 'Chuan Li' buds.7.Polyamines affected the transmission of root dormancy signals.The bound Cad is strongly associated with the signal entering the true dormancy,while the free Spd is closely related to the dormant release signal.