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Superoxide dismutases of chestnut leaves, Castanea sativa: Characterization and study of their involvement in natural leaf senescence

Authors

  • M. Angeles Longa,

    1. Unidad de Fisialogía Vegetal, Inst, de Investigaciones Agrobiológical dc Galicia, CSIC. Apdo 122. E-15080 Santiago de Compsotela. Spain.
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    • M. A. Longa (present address: Dpto de Genetica. Facultad de Veterinaria, E-27002 Lugo, Spain)

  • Luis A. del Río,

    1. Unidad de Fisialogía Vegetal, Inst, de Investigaciones Agrobiológical dc Galicia, CSIC. Apdo 122. E-15080 Santiago de Compsotela. Spain.
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  • Josè M. Palma

    Corresponding author
    1. Unidad de Fisialogía Vegetal, Inst, de Investigaciones Agrobiológical dc Galicia, CSIC. Apdo 122. E-15080 Santiago de Compsotela. Spain.
      J. M. Palma (corresponding author: present address: Dpto de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín. CSIC, Apdo) 419, E-18080 Granada, Spain)
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J. M. Palma (corresponding author: present address: Dpto de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín. CSIC, Apdo) 419, E-18080 Granada, Spain)

Abstract

Superoxide dismutases (SOD; EC 1.15.1.1) in chestnut (Castanea sativa Mill., cv. 431) leaves were characterized by native polyacrylamide gel electrophoresis. The three molecular forms of SOD were distinguished from each other by their different sensitivity to cyanide and H2O2 Three CuZn-containing SODs were detected (CuZn-SOD I, II. and III), and all the isozymes had a molecular mass of 33 kDa. CuZn-SOD III was the most abundant isozyme. whereas CuZn-SOD II was present in a minor amount. In leaves showing typical symptoms of senescence increases of 2.5-. 7- and 4-fold in the specific activities of CuZn-SODs I, II, and III. respectively, were found. In addition, the pattern of the three isozymes was modified by the age of leaves, a rise in the CuZn-SOD II and a decrease in the CuZn-SOD 1 percentages being found in senescent leaves compared to green leaves. As to other activated oxygen-related enzymes, an increase in the superoxide-generating xanthine oxidase activity and a decline in both catalase and peroxidase activities during natural senescence of chestnut leaves were observed. Results obtained suggest that in natural senescence of chestnut leaves activated oxygen species are involved, and an overproduction of hydrogen peroxide and superoxide radicals probably takes place.

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