Antioxidative protection in the leaves of dark-senescing intact barley seedlings |
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Authors: | Email author" target="_blank">Lyudmila?Petrova?Simova-StoilovaEmail author Klimentina?Nikolova?Demirevska-Kepova Zlatimira?Petrova?Stoyanova |
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Institution: | (1) Institute of Plant Physiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria;(2) Institute of Plant Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bldg 21, 1113 Sofia, Bulgaria |
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Abstract: | In order to elucidate the possibility of in vivo oxidative modification of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase, EC 4.1.1.39) as a triggering mechanism
for its preferential degradation early in senescence, some antioxidant compounds, protective enzymes, H2O2 and protein carbonylation levels were studied in the leaves during dark-induced senescence of barley (Hordeum vulgare L. cv. “Obzor”) seedlings. Analyses were performed in extracts as well as in purified chloroplasts. Some weakening of the
antioxidative protection was detected during the treatment: diminution in the ascorbate and non-protein SH (mainly glutathione)
pools, lower activities of superoxide dismutase, guaiacol and ascorbate peroxidases. However, no accumulation of H2O2 was found, lower level of protein carbonylation in darkness was measured and the percentage of reduced ascorbate was maintained
high. Data concerning antioxidant compounds in chloroplasts revealed some impairment of the ascorbate and glutathione pools
under induced senescence - the level of non-protein thiols declined during early senescence whereas the ascorbate pool was
not significantly changed. The percentage of reduced ascorbate remained high in the chloroplasts and the activities of superoxide
dismutase and of ascorbate peroxidase were conserved. Taken together the results are not in accordance with the possibility
of in vivo oxidative modification of Rubisco in the case of dark-induced senescence. Our data bring some support to the view about redox
regulation of Rubisco turnover in senescence through the pool of the low-molecular chloroplastic thiols. |
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Keywords: | barley (Hordeum vulgare L ) dark-induced senescence oxidative stress |
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