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The STUDIA UNIVERSITATIS BABEŞ-BOLYAI issue article summary
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Abstract: The activity of antioxidative enzymes was investigated under light stress, low temperatures and in the presence of certain photosynthetic inhibitors, during the state transitions of the exponentially Mougeotia cultures. The activity of SOD and GR has been enhanced, excluding the anaerobiosis conditions induced by FCCP, which have lead to the decrease of oxygen production - the main source of the reactive oxygen species. Blocking the PS II by DCMU, the cyclic electrons flow around the PS I operates at highest rate. In the conditions of intense light, low temperature and anaerobiosis, the activity of the ascorbate peroxidase has been intensified. The activity of monodehydroascorbate reductase has decreased, excepting the state of anaerobiosis. Moreover, the activity of dehydroascorbate reductase and NADPH dehydrogenase has significantly decreased both under intense light and low temperatures, and also in anaerobiosis or in the state transition of the photosystems. Under light stress and low temperature, the lipids peroxidation has been enhanced, probably due to the oxidative damages. When the photosynthetic inhibitor DCMU has been added during the state 2, the lipids peroxidation activity has been enhanced two times. The maintenance of the electrons flow from the thylakoids is essential for the chloroplasts protection against the photooxidative stress, this being a process in which the cyclic electrons flow and the water-water cycle also contribute. |
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