| Carbon monoxide(CO) is a double atoms gas molecule,also considered as a toxic gas in the pollution air for a long time.Recently in animal tissues,ample results have illustrated that CO was an important signaling molecule,participating in the regulation of multiple physiological and pathological processes.Recently Arabidopsis heme oxygenase gene as a major source of CO had been cloned and expressed in E.coli and proved that it could produce CO in vitro,suggeesting that plants could generate endogenous CO by HO in vivo.More recently,we discovered that CO played a major role in the regulation of plant development and stress tolerance,including the regulation of stomatal closure in Vicia faba,induction adventitious rooting of mung bean seedling,promotion lateral root formation in rapeseed,and improvement biomass in rice under salt stress and so on.In this study we use cut rose and wheat primary root to discover the further functions of CO in plant senescence and programmed cell death.The main topics of this thesis are as follows:1 Effects of exogenous CO donor hematin on vase life and antioxidative metabolism in cut rose flowerEffects of exogenous CO donor(hematin) at 0(control),0.001,0.01 and 0.1μmol·L-1on vase life and antioxidative metabolism in cut rose 'Movie Star' flower were investigated.Compared with the control flowers kept in distilled water, application of CO donor hematin(0-0.01μmol·L-1) exhibited different effects on the vase life of cut rose in a dose-dependent manner.Among of these,the effect of 0.01μmol·L-1 hematin(H0.01) was the most effective in extending the vase life.Whereas the opposite effect of 0.1μmol·L-1 hematin(H0.1) was also found.Furthermore, application of H0.01 apparently and differentially up-regulated the activities of peroxidase,catalase and superoxide dismutase,thus resulting in the apparent alleviation of lipid peroxidation during the early holding period.2 Effects of CO on salt-induced programmed cell death in wheat primary rootDifferent concentrations(100 mmol·L-1-400 mmol·L-1) of NaCl dose-dependently inhibit the growth of wheat primary root,but decrease in their HO activity.We discovered that the addition of varying concentrations of CO-saturated aqueous solutions(5%,50%and 100%) could significantly allay the growth inhibition of wheat primary root and PCD elicited by salt stress(200 mmol·L-1 NaCl),including decreased DNA laddering and the rate of positive TUNEL stain nucleus.Treatment with 50%CO-saturated aqueous solution improved the growth rate of wheat primary root by 13.42%and attenuated the rate of positive TUNEL stain by 26.36%compared with only salt treatment.At the same time degree of nuclear condensation and marginalization was attenuated at root growing point.These indicated that CO may improve growth inhibition of wheat primary root by attenuateing PCD.Furthermore,we observed that CO was able to up-regulate the profile of SOD (Mn-SOD and Cu/Zn-SOD) expression and down-regulate the profile of NADPH oxidase expression,resulted in reduction of the content of super oxide anion in wheat primary root.Consequently it improves the growth inhibition of wheat primary root under salt stress.Growth rate of wheat primary root treated by the special super oxide scavenger(Tiron),NADPH oxidase inhibitor(Apocynin) and Cu/Zn-SOD inhibitor (DETC)combined with 50%CO-saturated aqueous solution under salt stress, indicated that the two former chemicals could improve growth inhibition of wheat primary root,but less than the effects of 50%CO-saturated aqueous solution treatment.Whereas,DETC could effectively reverse the improvement of 50% CO-saturated aqueous solution treatment.These data suggested the CO could not only improve growth of wheat primary root under salt stress by regulation of the content of superoxide in the root,but also by another way.
|
PDF Full Text Request