Abscisic acid-induced apoplastic H2O2 accumulation up-regulates the activities of chloroplastic and cytosolic antioxidant enzymes in maize leaves

Abstract

The histochemical and cytochemical localization of abscisic acid (ABA)-induced H(2)O(2) production in leaves of maize (Zea mays L.) plants were examined, using 3,3-diaminobenzidine (DAB) and CeCl(3) staining, respectively, and the relationship between ABA-induced H(2)O(2) production and ABA-induced subcellular activities of antioxidant enzymes was studied. H(2)O(2) generated in response to ABA treatment was detected within 0.5 h in major veins of the leaves and maximized at about 2-4 h. In mesophyll and bundle sheath cells, ABA-induced H(2)O(2) accumulation was observed only in apoplast, and the greatest accumulation occurred in the walls of mesophyll cells facing large intercellular spaces. Meanwhile, ABA treatment led to a significant increase in the activities of the leaf chloroplastic and cytosolic antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), and pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI), the O (2) (-) scavenger Tiron and the H(2)O(2) scavenger dimethylthiourea (DMTU) almost completely arrested the increase in the activities of these antioxidant enzymes. Our results indicate that the accumulation of apoplastic H(2)O(2) is involved in the induction of the chloroplastic and cytosolic antioxidant enzymes. Moreover, an oxidative stress induced by paraquat (PQ), which generates O (2) (-) and then H(2)O(2) in chloroplasts, also up-regulated the activities of the chloroplastic and cytosolic antioxidant enzymes, and the up-regulation was blocked by the pretreatment with Tiron and DMTU. These data suggest that H(2)O(2) produced at a specific cellular site could coordinate the activities of antioxidant enzymes in different subcellular compartments.

Role of abscisic acid and drought stress on the activities of antioxidant enzymes in wheat

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Global plant-responding mechanisms to salt stress: physiological and molecular levels and implications in biotechnology

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The High Light Response inArabidopsisInvolves ABA Signaling between Vascular and Bundle Sheath Cells

“…To verify accumulation of extracellular H 2 O 2 in HL-exposed leaves, we used transmission electron microscopy to visualize cerium perhydroxide deposits, formed by reaction of infiltrated cerium trichloride (CeCl 3 ) with H 2 O 2 (Bestwick et al, 1997;Hu et al, 2005). Dark cerium perhydroxide deposits were detected in the apoplast adjoining cells of the bundle sheath and the 2148 The Plant Cell (Fryer et al, 2003;Mullineaux et al, 2006).…”