Arabidopsis CALCIUM-DEPENDENT PROTEIN KINASE8 and CATALASE3 Function in Abscisic Acid-Mediated Signaling and H₂O₂ Homeostasis in Stomatal Guard Cells under Drought Stress

Abstract

Drought is a major threat to plant growth and crop productivity. Calcium-dependent protein kinases (CDPKs, CPKs) are believed to play important roles in plant responses to drought stress. Here, we report that Arabidopsis thaliana CPK8 functions in abscisic acid (ABA)-and Ca 2+ -mediated plant responses to drought stress. The cpk8 mutant was more sensitive to drought stress than wild-type plants, while the transgenic plants overexpressing CPK8 showed enhanced tolerance to drought stress compared with wild-type plants. ABA-, H 2 O 2 -, and Ca 2+ -induced stomatal closing were impaired in cpk8 mutants. Arabidopsis CATALASE3 (CAT3) was identified as a CPK8-interacting protein, confirmed by yeast two-hybrid, coimmunoprecipitation, and bimolecular fluorescence complementation assays. CPK8 can phosphorylate CAT3 at Ser-261 and regulate its activity. Both cpk8 and cat3 plants showed lower catalase activity and higher accumulation of H 2 O 2 compared with wild-type plants. The cat3 mutant displayed a similar drought stress-sensitive phenotype as cpk8 mutant. Moreover, ABA and Ca 2+ inhibition of inward K + currents were diminished in guard cells of cpk8 and cat3 mutants. Together, these results demonstrated that CPK8 functions in ABA-mediated stomatal regulation in responses to drought stress through regulation of CAT3 activity.

Study of the Interactive Effects of Calcium and Abscisic Acid on Drought Stressed Triticum aestivum Seedlings

“…Drought is one of the main abiotic stresses which adversely affects crop growth and yield (Zou et al, 2015). In the present study, drought stress (applied as PEG, 20%) resulted in a significant reduction in shoot fresh and dry weights of Triticum aestivum seedlings (Fig.…”

Nucleoredoxin guards against oxidative stress by protecting antioxidant enzymes

“…Consequently, during periods of oxidative stress, PEX recycling is blocked, resulting in decreased peroxisomal import of PEX5 targets, including catalase (25). Accordingly, a recent report demonstrated that pathogen-mediated transient expression of CAT3 in tobacco leaves resulted in its localization to the peroxisome, cytoplasm, and plasma membrane (27). Our findings suggest that oxidation-induced retention of catalases in the cytoplasm may enable these critical detoxifying enzymes to become substrates of NRX1.…”

What is the role of hydrogen peroxide in plant peroxisomes?

“…In maize plants exposed to drought conditions, there is a high accumulation of H 2 O 2 in both guard cells and subsidiary cells, resulting in stomatal closure (Yao et al 2013). Thus, this closely correlates with some changes in Arabidopsis where catalase 3 modulates H 2 O 2 homeostasis in stomatal guard cells (Zou et al 2015). Additionally, it has also been reported using Arabidopsis knockout mutants of the peroxisomal NADP-dependent isocitrate dehydrogenase (ICDH; activity participating in detoxification of H 2 O 2 through the ascorbate-glutathione cycle by providing NADPH for glutathione reductase) that peroxisomes are involved in stomatal movement, supporting the suggestion that these organelles are a new element in the signalling network of guard cells (Leterrier et al 2015).…”

“…Genetic approaches, using Arabidopsis mutants such as the so-called NCA1 (no catalase activity 1), with extremely low catalase activity, have enabled a link between ROS and autophagy-dependent cell death promotion to be established (Hackenberg et al 2013). Very recently, it has also been shown that a Ca-dependent protein kinase can phosphorylate Cat-3 at Ser-261 and regulate their activity by mediating H 2 O 2 homeostasis in stomatal guard cells under drought stress conditions (Zou et al 2015).…”