Calcium-sensing receptor regulates stomatal closure through hydrogen peroxide and nitric oxide in response to extracellular calcium in Arabidopsis

Abstract

The Arabidopsis calcium-sensing receptor CAS is a crucial regulator of extracellular calcium-induced stomatal closure. Free cytosolic Ca2+ (Ca2+i) increases in response to a high extracellular calcium (Ca2+o) level through a CAS signalling pathway and finally leads to stomatal closure. Multidisciplinary approaches including histochemical, pharmacological, fluorescent, electrochemical, and molecular biological methods were used to discuss the relationship of hydrogen peroxide (H2O2) and nitric oxide (NO) signalling in the CAS signalling pathway in guard cells in response to Ca2+o. Here it is shown that Ca2+o could induce H2O2 and NO production from guard cells but only H2O2 from chloroplasts, leading to stomatal closure. In addition, the CASas mutant, the atrbohD/F double mutant, and the Atnoa1 mutant were all insensitive to Ca2+o-stimulated stomatal closure, as well as H2O2 and NO elevation in the case of CASas. Furthermore, it was found that the antioxidant system might function as a mediator in Ca2+o and H2O2 signalling in guard cells. The results suggest a hypothetical model whereby Ca2+o induces H2O2 and NO accumulation in guard cells through the CAS signalling pathway, which further triggers Ca2+i transients and finally stomatal closure. The possible cross-talk of Ca2+o and abscisic acid signalling as well as the antioxidant system are discussed.

Chloroplast-mediated activation of plant immune signalling in Arabidopsis

“…S15 ), suggesting a limited role of NADPH oxidase-derived O 2 − and H 2 O 2 in CAS-dependent immune responses. In addition, it has been recently shown by another group that extracellular Ca 2 + -induced generation of chloroplast NO and ROS is dependent on CAS, but not plasma membrane-localized NADPH oxidase 35 , providing further confi rmation of the role of CAS in ROS production in chloroplasts. Th us, we assume that CAS may be involved in the chloroplast-derived 1 O 2 -mediated retrograde signalling that regulates the expression of nuclear-encoded defence-related genes at an early stage in PTI.…”

Reactive Oxygen Species in the Regulation of Stomatal Movements

“…Numerous studies have demonstrated chloroplastic ROS accumulation following ABA treatment (Pei et al, 2000;Zhang et al, 2001b), extracellular Ca 2+ (Nomura et al, 2008;Wang et al, 2012), ozone (Joo et al, 2005;Vahisalu et al, 2010), and other stimuli leading to stomatal closure. Following these discoveries, hypotheses of the regulatory role of chloroplast-dependent ROS accumulation in stomatal movements have been drawn (Sierla et al, 2013).…”

Comparison of global responses to mild deficiency and excess copper levels in Arabidopsis seedlings

“…53 Indeed, several genes related to ABA signalling were overrepresented under high Cu conditions (Table S1, ESI †). Moreover Ca 2+ fluxes and ROS production have already been reported to participate in both Cu signalling 54 and circadian rhythm regulation.…”