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

Abstract

Summary• 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.

Divergences in Hormonal and Enzymatic Antioxidant Responses of Two Chicory Ecotypes to Salt Stress1

“…Regardless of the absolute amount of ABA, the slope shift observed at 6 dS m -1 for both ecotypes versus salinity is noticeable and this was more pronounced in Siyah Shiraz ecotype than Sefid Shiraz one. These results are consistent with those of Yang et al (2014) and Lovelli et al (2012) in tomato (Solanum lycopersicum) and Hu et al (2006) in maize (Zea mays), who reported that salt tolerant plants contain more ABA concentration than sensitive ones. In addition, ABA activates the expression of genes encoding antioxidant enzymes, increasing the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) (Yang et al, 2014).…”

“…Under salt stress, ABA levels increased dramatically with increased salinity in chicory ecotypes leaves (Figure 4), suggesting that ABA acts as a signal in salt response. ABA controls many stress adaptation responses, including stomatal closure, activation of genes involved in osmotic adjustment, ion compartimentation, regulation of shoot versus root growth and modifications of root hydraulic conductivity properties (Jiang et al, 2002;Zhang et al, 2006;Hu et al, 2006;Antoni et al, 2011;Javid et al, 2011). Regardless of the absolute amount of ABA, the slope shift observed at 6 dS m -1 for both ecotypes versus salinity is noticeable and this was more pronounced in Siyah Shiraz ecotype than Sefid Shiraz one.…”

“…In addition, ABA activates the expression of genes encoding antioxidant enzymes, increasing the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) (Jiang & Zhang, 2002;Yang et al, 2014). The increased capacity of reactive oxygen species (ROS) scavenging alleviates the damaging effect of ROS on fat/oil and protein (Hu et al, 2006). ABA also plays critical roles in reducing stomatal conductance and inducing the expression of genes responsible for various osmolytes synthesis, such as proline and betaine (Jung et al, 2008;Antoni et al, 2011).…”

Cross-talk between calcium-calmodulin and nitric oxide in abscisic acid signaling in leaves of maize plants

“…Accumulating evidence indicates that ABAenhanced water stress tolerance is, at least in part, due to the induction of antioxidant defense systems [3][4][5][6]. Previous studies have shown that NADPH oxidase, hydrogen peroxide (H 2 O 2 ), nitric oxide (NO), calcium (Ca 2+ )-calmodulin (CaM), and mitogen-activated protein kinase (MAPK) are required for ABA-induced up-regulation in the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) and glutathione reductase (GR) in leaves of maize plants [7][8][9][10][11]. It has been shown that ABA-induced H 2 O 2 production mediates NO generation, which, in turn, activates MAPK and results in the up-regulation in the expression and the activities of antioxidant enzymes in ABA signaling [11].…”

“…It has been shown that ABA-induced H 2 O 2 production mediates NO generation, which, in turn, activates MAPK and results in the up-regulation in the expression and the activities of antioxidant enzymes in ABA signaling [11]. Ca 2+ -CaM has also been shown to be necessary for ABAinduced antioxidant defense and function both upstream and downstream of H 2 O 2 production in leaves of maize plants [9]. However, whether Ca 2+ -CaM is involved in NO-induced antioxidant defense in plants and, if so, what the relationship between Ca 2+ -CaM and NO in the ABA signaling is remains to be determined.…”