Natural senescence of pea leaves. An activated oxygen-mediated function for peroxisomes

• Published in: Plant physiology (Bethesda) 1997-02, Vol.113 (2), p.411-418
• Main Authors: PASTORI, G. M, DEL RIO, L. A
• Format: Article
• Language: English
• Subjects: actividad enzimatica; activite enzymatique; Agronomy. Soil science and plant productions; avejentamiento; Biological and medical sciences; catalasa; catalase; Cell Biology and Signal Transduction; cell structure; Cellular senescence; ciclo del glioxilato; cobre; copper; cuivre; cycle du glyoxylate; cytoplasmic organelles; darkness; developmental stages; Economic plant physiology; Enzymes; enzymic activity; estructura celular; etapas de desarrollo; feuille; Fundamental and applied biological sciences. Psychology; glyoxylate cycle; Glyoxysomes; Growth and development; hojas; isocitrate lyase; isocitrato liasa; isoenzimas; isoenzyme; isoenzymes; Leaves; light; lumiere; luz; metabolism; metabolisme; metabolismo; Mitochondria; mitochondrie; mitocondria; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; obscuridad; obscurite; organite cellulaire; organulos citoplasmicos; oxidoreductases; oxidorreductasas; oxigeno; oxydoreductase; Oxygen; Oxygen metabolism; oxygene; Peas; Peroxisomes; pisum sativum; Plant physiology and development; purificacion; purification; senescence; Senescence and abscission; stade de developpement; structure cellulaire; superoxide dismutase; Superoxides; superoxido dismutasa; superoxyde dismutase; ultraestructura; ultrastructure; Vegetative apparatus, growth and morphogenesis. Senescence; xanthine oxidase; xanthine oxydase; xantina oxidasa
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.2.411

We studied the activated oxygen metabolism of peroxisomes in naturally and dark-induced senescent leaves of pea (Pisum sativum L.). Peroxisomes were purified from three different types of senescent leaves and the activities of different peroxisomal and glyoxysomal enzymes were measured. The activities of the O2.- -producing and H2O2-producing enzymes were enhanced by natural senescence. Senescence also produced an increase in the generation of active oxygen species (O2.- and H2O2) in leaf peroxisomes and in the activities of two glyoxylate-cycle marker enzymes. A new fraction of peroxisomes was detected at an advanced stage of dark-induced senescence. Electron microscopy revealed that this new peroxisomal fraction varied in size and electron density. During senescence, the constitutive Mn-superoxide dismutase (SOD) activity of peroxisomes increased and two new CuZn-SODs were induced, one of which cross-reacted with an antibody against glyoxysomal CuZnSOD. This fact and the presence of glyoxylate-cycle enzymes support the idea that foliar senescence is associated with the transition of peroxisomes into glyoxysomes. Our results indicate that natural senescence causes the same changes in peroxisome-activated oxygen metabolism as dark-induced senescence, and reinforce the hypothesis of an effective role of peroxisomes and their activated oxygen metabolism in this stage of the life cycle.