Cytokinins are mobile multifunctional plant hormones with roles in development and stress resilience. Although their Histidine Kinase receptors are substantially localised to the endoplasmic reticulum, cellular sites of cytokinin perception and importance of spatially heterogeneous cytokinin distribution continue to be debated. Here we show that cytokinin perception by plasma membrane receptors is an effective additional path for cytokinin response. Readout from a Two Component Signalling cytokinin-specific reporter (TCSn::GFP) closely matches intracellular cytokinin content in roots, yet we also find cytokinins in extracellular fluid, potentially enabling action at the cell surface. Cytokinins covalently linked to beads that could not pass the plasma membrane increased expression of both TCSn::GFP and Cytokinin Response Factors. Super-resolution microscopy of GFP-labelled receptors and diminished TCSn::GFP response to immobilised cytokinins in cytokinin receptor mutants, further indicate that receptors can function at the cell surface. We argue that dual intracellular and surface locations may augment flexibility of cytokinin responses.
We thank Bruno Müller and Aaron Rashotte for critical discussions and provision of plant lines used in this work, Roger Granbom and Tamara Hernández Verdeja (UPSC, Umeå, Sweden) for technical assistance and providing materials, Zuzana Pěkná and Karolina Wojewodová (CRH, Palacký University, Olomouc, Czech Republic) for help with cytokinin receptor binding assays, and David Zalabák (CRH, Palacký University, Olomouc, Czech Republic) for provision of vector pINIIIΔEH expressing CRE1/AHK4. The bioimaging facility of IST Austria, the Swedish Metabolomics Centre and the IST Austria Bio-Imaging facility are acknowledged for support. The work was funded by the European Molecular Biology Organization (EMBO ASTF 297-2013) (I.A.), Development—The Company of Biologists (DEVTF2012) (I.A.; C.T.), Plant Fellows (the International Post doc Fellowship Programme in Plant Sciences, 267423) (I.A.; K.L.), the Swedish Research Council (621-2014-4514) (K.L.), UPSC Berzelii Center for Forest Biotechnology (Vinnova 2012-01560), Kempestiftelserna (JCK-2711) (K.L.) and (JCK-1811) (E.-M.B., K.L.). The Ministry of Education, Youth and Sports of the Czech Republic via the European Regional Development Fund-Project “Plants as a tool for sustainable global development” (CZ.02.1.01/0.0/0.0/16_019/0000827) (O.N., O.P., R.S., V.M., L.P., K.D.) and project CEITEC 2020 (LQ1601) (M.P., J.H.) provided support, as did the Czech Science Foundation via projects GP14-30004P (M.P.) and 16-04184S (O.P., K.D., O.N.), Vetenskapsrådet and Vinnova (Verket för Innovationssystem) (T.V., S.R.), Knut och Alice Wallenbergs Stiftelse via “Shapesystem” grant number 2012.0050. A.J. was supported by the Austria Science Fund (FWF): I03630 to J.F. The research leading to these results received funding from European Union’s Horizon 2020 programme (ERC grant no. 742985) and FWO-FWF joint project G0E5718N to J.F.
Antoniadi I, Novák O, Gelová Z, et al. Cell-surface receptors enable perception of extracellular cytokinins. Nature Communications. 2020;11. doi:10.1038/s41467-020-17700-9
Antoniadi, I., Novák, O., Gelová, Z., Johnson, A. J., Plíhal, O., Simerský, R., … Turnbull, C. (2020). Cell-surface receptors enable perception of extracellular cytokinins. Nature Communications, 11. https://doi.org/10.1038/s41467-020-17700-9
Antoniadi, Ioanna, Ondřej Novák, Zuzana Gelová, Alexander J Johnson, Ondřej Plíhal, Radim Simerský, Václav Mik, et al. “Cell-Surface Receptors Enable Perception of Extracellular Cytokinins.” Nature Communications 11 (2020). https://doi.org/10.1038/s41467-020-17700-9.
I. Antoniadi et al., “Cell-surface receptors enable perception of extracellular cytokinins,” Nature Communications, vol. 11, 2020.
Antoniadi I, Novák O, Gelová Z, Johnson AJ, Plíhal O, Simerský R, Mik V, Vain T, Mateo-Bonmatí E, Karady M, Pernisová M, Plačková L, Opassathian K, Hejátko J, Robert S, Friml J, Doležal K, Ljung K, Turnbull C. 2020. Cell-surface receptors enable perception of extracellular cytokinins. Nature Communications. 11.
Antoniadi, Ioanna, et al. “Cell-Surface Receptors Enable Perception of Extracellular Cytokinins.” Nature Communications, vol. 11, 4284, Springer Nature, 2020, doi:10.1038/s41467-020-17700-9.