Effects of growth regulators and light on chloroplasts NAD(P)H dehydrogenase activities of senescent barley leaves |
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Authors: | Juan Cuello María José Quiles Joaquín Rosauro Bartolomé Sabater |
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Institution: | (1) Departamento de Biología Vegetal, Facultad de Biología, Universidad de Murcia, E-30100 Murcia, Spain;(2) Departamento de Biología Vegetal, Universidad de Alcalá de Henares, Alcalá de Henares, E-28871 Madrid, Spain |
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Abstract: | The activities NADH and NADPH dehydrogenases were measured with ferricyanide as electron-acceptor (NADH-FeCN-ox and NADPH-FeCN-ox, respectively) in mitochondria-free chloroplasts of barley leaf segments after receiving various treatments affecting senescence. NADPH-FeCN-ox declined during senescence in the dark, in a way similar to chlorophyll and Hill reaction, and increased when leaf segments were incubated at light. These results suggest that NADPH-FeCN-ox is related to some photosynthetic electron transporter activity (probably ferredoxin-NADP+ oxidoreductase). In contrast, NADH-FeCN-ox is notably stable during senescence in the dark and at light. This activity increased during incubation with kinetin or methyl-jasmonate (Me-JA) but decreased when leaf segments were treated with abscisic acid (ABA). The effects of the inhibitors of protein synthesis cycloheximide and chloramphenicol suggest that the changes of NAD(P)H dehydrogenase activities may depend on protein synthesis in chloroplasts. In senescent leaf, chloroplast NADH dehydrogenase might be a way to dissipate NADH produced in the degradation of excess carbon which is released from the degradation of amino acids.Abbreviations ABA
abscisic acid
- DCPIP
2,6-dichlorophenol-indo-phenol
- DOC
deoxycholate
- Me-JA
methyl jasmonate
- NADH-FeCN-ox
NADH ferricyanide oxidoreductase
- NADPH-FeCN-ox
NADPH ferricyanide oxidoreductase |
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Keywords: | abscisic acid barley (Hordeum vulgare) chloroplasts kinetin methyl-jasmonate NADH dehydrogenase NADPH dehydrogenase |
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