In plants, the multistep phosphorelay (MSP) pathway mediates a range of regulatory processes, including those activated by cytokinins. The crosstalk between cytokinin response and light is known for a long time. However, the molecular mechanism underlying the interactionbetween light and cytokinin signaling remains elusive. In the screen for upstream regulators we identified a LONG PALE HYPOCOTYL (LPH) gene whose activity is indispensable for spatiotemporally correct expression of CYTOKININ INDEPENDENT-1 (CKI1), encoding the constitutively active sensor histidine kinase that activates MSP signaling. lph is a new allele of HEME OXYGENASE 1 (HY1) which encodes the key protein in the biosynthesis of phytochromobilin, a cofactor of photoconvertiblephytochromes. Our analysis confirmed the light-dependent regulation oftheCKI1 expression pattern. We show that CKI1 expression is under the control of phytochrome A (phyA), functioning as a dual (both positive and negative) regulator of CKI1 expression, presumably via the phyA-regulated transcription factors PHYTOCHROME INTERACTING FACTOR 3 (PIF3) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1). Changes in CKI1 expression observed in lph/hy1-7 and phy mutants correlatewithmisregulation of MSP signaling, changedcytokinin sensitivity and developmental aberrations,previously shown to be associated with cytokinin and/or CKI1 action. Besides that, we demonstrate novel role of phyA-dependent CKI1 expression in the hypocotyl elongation and hook development during skotomorphogenesis. Based on these results, we propose that the light-dependent regulation of CKI1 provides a plausible mechanistic link underlying the well-known interaction between light- and cytokinin-controlled plant development.
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Dobisova T, Hrdinova V, Cuesta C, et al. Light regulated expression of sensor histidine kinase CKI1 controls cytokinin related development. Plant Physiology. 2017;174(1):387-404. doi:10.1104/pp.16.01964
Dobisova, T., Hrdinova, V., Cuesta, C., Michlickova, S., Urbankova, I., Hejatkova, R., … Hejátko, J. (2017). Light regulated expression of sensor histidine kinase CKI1 controls cytokinin related development. Plant Physiology. American Society of Plant Biologists. https://doi.org/10.1104/pp.16.01964
Dobisova, Tereza, Vendula Hrdinova, Candela Cuesta, Sarka Michlickova, Ivana Urbankova, Romana Hejatkova, Petra Zadnikova, Markéta Pernisová, Eva Benková, and Jan Hejátko. “Light Regulated Expression of Sensor Histidine Kinase CKI1 Controls Cytokinin Related Development.” Plant Physiology. American Society of Plant Biologists, 2017. https://doi.org/10.1104/pp.16.01964.
T. Dobisova et al., “Light regulated expression of sensor histidine kinase CKI1 controls cytokinin related development,” Plant Physiology, vol. 174, no. 1. American Society of Plant Biologists, pp. 387–404, 2017.
Dobisova T, Hrdinova V, Cuesta C, Michlickova S, Urbankova I, Hejatkova R, Zadnikova P, Pernisová M, Benková E, Hejátko J. 2017. Light regulated expression of sensor histidine kinase CKI1 controls cytokinin related development. Plant Physiology. 174(1), 387–404.
Dobisova, Tereza, et al. “Light Regulated Expression of Sensor Histidine Kinase CKI1 Controls Cytokinin Related Development.” Plant Physiology, vol. 174, no. 1, American Society of Plant Biologists, 2017, pp. 387–404, doi:10.1104/pp.16.01964.