The Research About Hydrogen Peroxide Signaling On Photosynthetic Characteristics Of Transgenic Rice Overexpressing Maize Pepc

The phosphoenolpymvate carboxylase(pepc) of maize,the crucial enzyme in C4photosynthetic pathway, has been transform into C3crop rice and highly expression successfully.The transgenic rice’s photosynthetic rate also been enhanced. Therefore it attracts more and more intention to improve C3crops photosynthetic efficiency by transforming C4-photosynthetic specialty. After that, an increasing number of research about rice breeding showed that pepc transgenic rice also has toleration to oxidation stress especial from high intensity light, and it was clearly related to the C4-pepc; As the important functional molecule of oxidation stress, hydrogen peroxide has many different way to generate,and plays an important role inside plant bodies. The work main investigate the relationship between photosynthetic specialty of C4-pepc transgenic rice (PC) and hydrogen peroxide signalling.The results as follows:1. Photosynthetic characteristics of PC and untransformed rice plant (WT) were investigated under different concentrate exogenous H2O2. As compared with WT, PN of PC treated with low level H2O20.5～5mmol/LH2O2descend as same as changing of Gs, and the inhibition are weaken as light intensity increasing. So H2O2of low concentrate might regulate Gs of PC to affect photosynthesis physiological characteristic.2. With method of regents inhale from petiole cut, those regents related to endogenous H2O2such as abscisic acid (ABA), phospholipase D inhibition n-butanol (BA), phospholipase C inhibition neomycin (NS) and diphenyleneiodonium (DPI) were applied: After ABA treatment, both PC and WT’s endogenous H2O2concentration were enhanced. As compared to WT, PC with BA and DPI treatments all can inhibit PC’s endogenous H2O2generation. This was similar to those results on measurement of endogenous H2O2.3. Then the affection of endogenous H2O2on PC’s PN was investigated. After treatment with DPI for30minutes, PC and WT behave differently, PN of WT does not change much, but that in PC appear enhanced. The results of Gs after DPI treatment were similar with BA. Statistical analysis shows that ABA and DPI treat make the significantly correlation coefficient between PN and Gs in PC. So both rising and failing down changes of endogenous H2O2promote the dedication of stoma factor to photosynthesis. Although the whole apparent chlorophyll fluorescence parameters changed less showing that the experimental plants are not under stress, due to the balance of the light energy conversion and heat dissipation, the stability of PSII of the rice plants have been obviously changed.On the whole, endogenous H2O2also can inhibit PEPCase activity by the results of the treatments of ABA or DPI, but no effect on pepc gene transcription and translation, so it might regulate as a post-translate regulation.