| 17176391 |
Hu X, Jiang M, Zhang J, Zhang A, Lin F, Tan M: Calcium-calmodulin is required for abscisic acid-induced antioxidant defense and functions both upstream and downstream of H2O2 production in leaves of maize (Zea mays) plants. New Phytol. 2007;173(1):27-38.
* Using pharmacological and biochemical approaches, the role of calmodulin (CaM) and the relationship between CaM and hydrogen peroxide (H (2) O (2)) in abscisic acid (ABA)-induced antioxidant defense in leaves of maize (Zea mays) plants were investigated. * Treatment with ABA or H (2) O (2) led to significant increases in the concentration of cytosolic Ca (2+) in the protoplasts of mesophyll cells and in the expression of the calmodulin 1 (CaM1) gene and the content of CaM in leaves of maize plants, and enhanced the expression of the antioxidant genes superoxide dismutase 4 (SOD4), cytosolic ascorbate peroxidase (cAPX), and glutathione reductase 1 (GR1) and the activities of the chloroplastic and cytosolic antioxidant enzymes. The up-regulation of the antioxidant enzymes was almost completely blocked by pretreatments with two CaM antagonists. * Pretreatments with CaM antagonists almost completely inhibited ABA-induced H (2) O (2) production throughout ABA treatment, but pretreatment with an inhibitor or scavenger of reactive oxygen species (ROS) did not affect the initial increase in the contents of CaM induced by ABA. * Our results suggest that Ca (2+)-CaM is involved in ABA-induced antioxidant defense, and that cross-talk between Ca (2+)-CaM and H (2) O (2) plays a pivotal role in ABA signaling. |
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