Abstract: The effect of spermidine and polyamine biosynthetical inhibitor-MGBG on endogenous polyamine contents and p rotein p rofiles of ovary and its correlation with cucumber parthenocarpy and ovary development were studied using parthenocarpic line EP26 and non-parthenocarp ic line ZR-2 treatedwith exogenous spermidine andMGBG. The resultswere as follows: the exogenous app lications of Spd at 1 mmol/L at 2 days before anthesis could significantly increase endogenous Spd, Spm and Put levels in the non-pollinated ovaries of ZR-2 at 2 days after anthesis, and the increasing in fruit length and fresh fruitmass could also be observed, which resulted in parthenocarp ic ovary ( young fruit) growth in the line ZR-2 when non-pollinated. However, the contents of Spd and Spm in the ovary of EP26, treated withMGBG, were decreased dramatically, while the content of Put was increased. The growth of fruit length and fresh fruit mass was inhibited, which led to ovary wither.
The results suggested that both Spd and Spm promote cucumber parthenocarpy and ovary (young fruit) growth. We also studied changes of specific protein profiles during ovary /young fruit development treated with exogenous Spd on ZR-2 andMGBG on EP26. The results showed that specific proteins of 88 kD, 82 kD, 55 kD and 37 kD were identified in the ovary/young fruit of ZR-2 with exogenous Spd application. Application of polyamine
biosynthesis inhibitorMGBG on EP26 ovary could induce the biosynthesis of specific proteins of 47 kD and 25 kD, but lead to the disappearance of the proteins of 85 kD, 45 kD and 10 kD. Those results indicated that exogenous application of Spd and MGBG might stimulate ovary/young fruit growth and induce parthenocarpy by regulating endogenous Spd and Spm levels and inducing the synthesis of some specific proteins.

Key words: Cucumber, Polyamine, Specific protein, Parthenocarpy