CIPK23 regulates blue light-dependent stomatal opening in Arabidopsis thaliana

Inoue, S.‐I. et al. (2020) CIPK23 regulates blue light-dependent stomatal opening in Arabidopsis thaliana. Plant Journal, 104(3), pp. 679-692. (doi: 10.1111/tpj.14955) (PMID:32780529)

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Phototropins (phot1 and phot2) are plant blue light receptor kinases that function to mediate phototropism, chloroplast movement, leaf flattening, and stomatal opening in Arabidopsis. Considerable progress has been made in understanding the mechanisms associated with phototropin receptor activation by light. However, the identities of phototropin signaling components are less well understood by comparison. In this study, we specifically searched for protein kinases that interact with phototropins by using an in vitro screening method (AlphaScreen) to profile interactions against an Arabidopsis protein kinase library. We found that CBL‐interacting protein kinase 23 (CIPK23) interacts with both phot1 and phot2. Although these interactions were verified by in vitro pull‐down and in vivo bimolecular fluorescence complementation assays, CIPK23 was not phosphorylated by phot1, as least in vitro. Mutants lacking CIPK23 were found to exhibit impaired stomatal opening in response to blue light but no deficits in other phototropin‐mediated responses. We further found that blue light activation of inward‐rectifying K+ (K+in) channels was impaired in the guard cells of cipk23 mutants, whereas activation of the plasma membrane H+‐ATPase was not. The blue light activation of K+in channels was also impaired in the mutant of BLUS1, which is one of the phototropin substrates in guard cells. We therefore conclude that CIPK23 promotes stomatal opening through activation of K+in channels most likely in concert with BLUS1, but through a mechanism other than activation of the H+‐ATPase. The role of CIPK23 as a newly identified component of phototropin signaling in stomatal guard cells is discussed.

Item Type:Articles
Additional Information:This work was supported, in part, by Japan Society for the Promotion of Science (JSPS) KAKENHI grants (nos. JP15K07101 and JP25840105 to S.I.), Grants-in-Aid for Scientific Research on Priority Areas (nos. JP17084005 and JP21227001 to K.S.), and the Hori Sciences And Arts Foundation (to S.I.). E.K. acknowledges the University of Glasgow for the award of a Lord Kelvin Adam Smith Fellowship. T.W. was supported by an MVLS DTP PhD studentship at the University of Glasgow.
Glasgow Author(s) Enlighten ID:Kaiserli, Dr Eirini and Christie, Professor John and OKUMURA, Dr MASAKI
Authors: Inoue, S.‐I., Kaiserli, E., Zhao, X., Waksman, T., Takemiya, A., Okumura, M., Takahashi, H., Seki, M., Shinozaki, K., Endo, Y., Sawasaki, T., Kinoshita, T., Zhang, X., Christie, J. M., and Shimazaki, K.‐I.
College/School:College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
Journal Name:Plant Journal
ISSN (Online):1365-313X
Published Online:11 August 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in Plant Journal 104(3): 679-692
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
171989Transcriptional regulation of plant growth in nuclear microdomainsEirini KaiserliBiotechnology and Biological Sciences Research Council (BBSRC)BB/M023079/1Institute of Molecular, Cell & Systems Biology
170684Photoreceptor Engineering to Modulate Plant GrowthJohn ChristieBiotechnology and Biological Sciences Research Council (BBSRC)BB/M002128/1MCSB - Plant Sciences
301413How do Phototropin Receptor Kinases Initiate Signalling from the PlasmaJohn ChristieBiotechnology and Biological Sciences Research Council (BBSRC)BB/R001499/1Institute of Molecular, Cell & Systems Biology