The Calcium-Dependent Protein Kinase CPK33 Mediates Strigolactone-Induced Stomatal Closure in Arabidopsis thaliana

Abstract

Strigolactones (SLs) are known to mediate plant acclimation to environmental stress. We recently reported that SLs acted as prominent regulators in promotion of stomatal closure. However, the detailed mechanism by which SLs induce stomatal closure requires further investigation. Here we studied the essential role of the calcium (Ca 2+) signal mediating by the calcium-dependent protein kinase (CPK) in SL-induced stomatal closure. SL-induced stomatal closure was strongly inhibited by a Ca 2+ chelator and Ca 2+ channel blockers, indicating that Ca 2+ functions in SL promotion of stomatal closure. Through examining a collection of cpk mutants, we identified CPK33, potentially acting as a Ca 2+ transducer, which is implicated in guard cell SL signaling. SL-and Ca 2+-induced stomatal closure were impaired in cpk33 mutants. CPK33 kinase activity is essential for SL induction of stomatal closure as SL-induced stomatal closure is blocked in the dead kinase mutant of CPK33. The cpk33 mutant is impaired in H 2 O 2-induced stomatal closure, but not in SLmediated H 2 O 2 production. Our study thus uncovers an important player CPK33 which functions as an essential Ca 2+ signals mediator in Arabidopsis guard cell SL signaling.

Identification and Expression Analysis of Calcium-Dependent Protein Kinases Gene Family in Potato Under Drought Stress

“…This report suggests that StCDPK proteins play a role in the tolerance of these cultivars to drought stress and supports the relationships among sequence, structure, and protein function. StCDPK13 was placed in the same phylogenetic group II as AtCPK21, AtCPK23 , and AtCPK33 , which have been reported to be involved in drought tolerance in Arabidopsis ( Ma and Wu, 2007 ; Geiger et al, 2011 ; Wang et al, 2019 ). StCDPK3/23 which Bi et al (2021) reported as having high expression levels in mannitol-induced drought stress was grouped in the same phylogenetic group III with OsCPK9 , which was also reported to play a role in drought tolerance in rice ( Wei et al, 2014 ).…”

Association genetics of early season cold and late season frost tolerance in Sorghum bicolor

“…Calcium is the second messenger in crop plants and responds to various signals such as touch, wind, gravity, light, cold, phytohormones, salt, and fungal elicitors (Braam & Davis, 1990; Bush, 1995; Poovaiah & Reddy, 1993). Calcium/calmodulin‐dependent protein kinases were reported to positively regulate cold (Abbasi et al., 2004), drought (Saijo et al., 2000; Urao et al., 1994), dehydration, salt stress (Hirayama et al., 1995; Ni et al., 2020; Pardo et al., 1998), stomatal closure (Huang et al., 2019; Wang et al., 2019b), and stomatal immunity (Thor et al., 2020) in various crop plants.…”

Integrative regulatory mechanisms of stomatal movements under changing climate

“…CPK21 can phosphorylate and activate the K + outward‐rectifying channel GORK (Hosy et al, 2003; van Kleeff et al, 2018). CPK33 is identified to play an important role in the Strigolactone‐induced stomatal closure in response to H 2 O 2 ‐triggered Ca 2+ signals (Wang et al, 2019). CBL1 and CBL9, plasma membrane‐localized calcineurin B‐like proteins, form a complex with CIPK23 to regulate its downstream target ion channels, including AKT1 (a voltage‐gated inward K + channel) and SLAC1, in guard cells to regulate stomatal aperture changes (Cheong et al, 2007; Huang et al, 2023a).…”