Subfamily <scp>C7</scp> Raf‐like kinases <scp>MRK1</scp>, <scp>RAF26</scp>, and <scp>RAF39</scp> regulate immune homeostasis and stomatal opening in <i>Arabidopsis thaliana</i>
The calcium-dependent protein kinase CPK28 regulates several stress pathways in multiple plant species. Here, we aimed to discover CPK28-associated proteins in Arabidopsis thaliana. We used affinity-based proteomics and identified several potential CPK28 binding partners, including the C7 Raf-like kinases MRK1, RAF26, and RAF39. We used biochemistry, genetics, and physiological assays to gain insight into their function. We define redundant roles for these kinases in stomatal opening, immune-triggered reactive oxygen species (ROS) production, and resistance to a bacterial pathogen. We report that CPK28 associates with and trans-phosphorylates RAF26 and RAF39, and that MRK1, RAF26, and RAF39 are active kinases that localize to endomembranes. Although Raf-like kinases share some features with mitogen-activated protein kinase kinase kinases (MKKKs), we found that MRK1, RAF26, and RAF39 are unable to trans-phosphorylate any of the 10 Arabidopsis mitogen-activated protein kinase kinases (MKKs). Overall, our study suggests that C7 Raf-like kinases associate with and are phosphorylated by CPK28, function redundantly in stomatal opening and immunity, and possess substrate specificities distinct from canonical MKKKs.
Authors
- Jacqueline Monaghan (ORCID: https://orcid.org/0000-0002-1770-1669)
- Frank L.H. Menke (ORCID: https://orcid.org/0000-0003-2490-4824)
- Anamika Rawat (ORCID: https://orcid.org/0000-0001-9081-3547)
- M. C. Rodriguez Gallo (ORCID: https://orcid.org/0000-0003-2171-6158)
- Kristen R. Siegel
- Jan Sklenář (ORCID: https://orcid.org/0000-0003-1858-2574)
- Cyril Zipfel (ORCID: https://orcid.org/0000-0003-4935-8583)
- R. Glen Uhrig (ORCID: https://orcid.org/0000-0003-2773-4381)
- Paul Derbyshire (ORCID: https://orcid.org/0000-0002-5095-9397)
- Márcia Gonçalves Dias (ORCID: https://orcid.org/0000-0002-0751-3920)
- Bassem Doss (ORCID: https://orcid.org/0009-0001-1867-3903)
- Tharika Mahathanthrige (ORCID: https://orcid.org/0009-0005-6564-3079)
- Thakshila Dharmasena (ORCID: https://orcid.org/0009-0009-3779-2455)
- Emma Cameron (ORCID: https://orcid.org/0000-0002-2325-2927)
Institutions
- University of East Anglia (GB)
- University of Alberta (CA)
- University of Zurich (CH)
- Queen's University (CA)
- Norwich Research Park (GB)
- Sainsbury Laboratory (GB)
Publication Details
- Journal
- New Phytologist
- Published
- 2024-10-24
- DOI
- https://doi.org/10.1111/nph.20198
- Citations
- 7
- Primary Topic
- Plant-Microbe Interactions and Immunity
- Type
- article
- Field-Weighted Citation Impact
- 4.20
Funders
- Universities Space Research Association
- Fundação de Amparo à Pesquisa do Estado de São Paulo
- Queen's University
- Ministry of Colleges and Universities
- Directorate for Biological Sciences
- Natural Sciences and Engineering Research Council of Canada
- Biotechnology and Biological Sciences Research Council
- Ontario Ministry of Research and Innovation