| In order to elucidate the relationship between cucumber(Cucmnis Sativus L) parthenocarpy and endogenous polyamine metabolism, we investigated the potential contribution of endogenous PAs metabolism to ovary/young fruit development with parthenocarpy line EP-6 and non-parthenocarpy line ZR-2, and analyzed the possible connection among endogenous PAs, nucleic acid and protein contents, and also investigated the effects of exogenous polyamines and their biosynthesis inhibitor (MGBG) on the endogenous polyamine level and cucumber ovary/young fruit development. We also studied changes of common protein and specific protein profiles during ovary /young fruit development. The comparative approach was used to analyze all experimental data. The preliminary results are summaried as follows:The non-fertilized ovary/young fruit of EP-6 can grow and develop normally as the same with fertilized one, but only fertilized ovary/young fruit of ZR-2 can grow, and non-pollinated ovary/young fruit whithered gradually since 3 DAA (days after anthesis).. Four free polyamines identified in both the ovaries of ZR-2 and EP-6 lines were spermidine (spd), spermine (spm), putrescine (put) and cadavarine (cad). The content of spd was highest throughout the whole ovary/young fruit growth stages but the levels of spd, put and cad were relatively lower. They reached the peak before 1d anthesis,thereafter gradually decreased with ovary development and then peaked again at2DAA.The first peak might correlate to the rapid cell proliferation of ovary at early stage, while the second might related with cell enlargement and differentiation of young cucumber embryo.In ZR-2 line, spd and spm levels were higher in pollinated ovary than non-fertilized one, except for put and cad levels. However, PAs exhibited the similar changes in both the two treated ovaries of EP-6, except that spd and spm levels were slightly higher in non-fertilized ovary. In all the development stages, cad content was negligible compared to those of spd, spm and put. The above analysis indicated that spd and spm could benefit cucumber parthenocarpy, while cad and put might have adverse effect on ovary/young fruit growth. Endogenous PA metabolism curve in the ovaries/ young fruits exhibited the same as that of RNA and protein. All of them peaked at about anthesis. The PAs contents especially spd and spm decreased, being accompanied by gradually decrease in RNA and protein levels with ovary growth, which suggested that endogenous PAs, especially spd and spm might stimulate cucumber ovary growth by regulating some biomacromolecular synthesis such as nucleic acid and protein.Endogenous PAs content in ZR-2 ovary exhibited the same changes as that of RNA and protein. PAs, especially spd and spm, and RNA and protein decreased gradually, however, PAs contents peaked earlier than protein, suggesting that endogenous PAs especially spd and spm might stimulate cucumber ovary growth by regulating some biomacromolecular synthesis such as nucleic acid and protein.The exogenous applications of spd and ssp (spd+spm+put) at 1mM could both cause a marked increases in endogenous spd, spm and put levels in the non-pollinatedovaries of ZR-2 DAA, compared with the pollinated one, and increase fruit length andfresh weight, resulting in normal ovary/young fruit growth when non-pollinated in the line ZR-2. However, the contents of spd and spm in the ovary of EP-6 treated with MGBG decreased dramatically but put level increased, and then inhibited the increase of fruit length and fresh weight, which led to ovary withering at later stages.Protein samples of cucumber ZR-2 and EP-6 lines were separated by SDS-PAGE method and stained with Coomassive Blue with different treatmens (fertilization and non-fertilization, exogenous spd and ssp treatments).The occurring or change of soluble specific proteins in cucumber ovary/young fruit was demonstrated as follows:In the ovaries of both lines, there emerged some specific proteins that differed both in their duration and variation... |
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