Cell Signalling Mechanisms in Plants


Plants use cell surface receptors belonging to histidine kinases or receptor‐like serine/threonine kinases to sense signals and to trigger responses through phosphorylation cascades. Signal‐dependent protein degradation is a prevalent regulatory mechanism in plants. Some of the plant hormones can directly modulate intracellular signalling components to exert their effect.

Keywords: plant hormones; plant development; G‐proteins; protein kinases; proteolysis

Figure 1.

Signalling with G‐proteins. (a) Monomeric GTPases, RAC/ROP. These operate by shuttling between the inactive GDP‐bound and the activated GTP‐bound forms that activate downstream effectors. (b) Heterotrimeric G protein‐coupled receptors (GPCRs). GPCRs have seven transmembrane spanning domains (orange). Binding of the agonist to GPCR stimulates its intrinsic GEF activity on Gα that allows GTP binding and dissociation of Gα and Gβγ subunits. Both these subunits can interact with downstream effectors (E1 and E2) and activate cellular responses.

Figure 2.

Hormone perceptions by cell surface receptors of the two‐component system. (a) The prototype of the so‐called two‐component phosphorelay signalling mechanism in prokaryotes. (b) The ethylene signal transduction. (c) The cytokinin signal transduction.

Figure 3.

Signalling with receptor‐like kinases. Upper panel illustrates the innate immunity signalling in response to the bacterial elicitor, flagellin, the clavata meristem maintenance signalling, the brassinosteroid hormone perception and the nod factor signalling during symbiosis. The lower panel shows the signalling pathway for the regulation of stomata density, the regulation of cell density‐dependent proliferation by the photosulfokine peptides (PSKs) and the systemic wound response signalled by the binding of the systemin peptide to the SR160 LRR–RLK receptor.

Figure 4.

Hormone perception involves direct binding to intracellular signalling proteins. (a) Auxin signal transduction. Within the cell the TIR1 and a small family of related F‐box proteins were identified as the auxin receptor. Dependent on auxin binding, TIR1 associates with the Aux/IAA transcriptional regulators and targets these for degradation. (b) Studies of giberellin signal transduction in rice revealed a conceptually similar mechanism to auxin. However, GA binds to an adaptor protein, GID1 and regulates the recruitment of the DELLA transcriptional repressor protein, called SLR1 in rice, to the F‐box protein, GID2 and thus SLR1 is targeted for degradation. (c) Central to JA‐signalling is also an F‐box protein, COI1, which is part of an E3 Ubiquitin ligase complex. How JA signalling operates is less understood; we only know some of the components involved. (d) ABA is mostly known for its effects during dormancy. Recently, it was found to regulate flowering time by binding to the FCA protein and thereby disrupting its interaction with FY. The FCA–FY complex prevents the accumulation of the FLC mRNA. FLC is a potent repressor of flowering.

Figure 5.

Light signalling mechanisms. (a) The rapid pathway. Red/far red light induces the conversion of phytochrome B (phyB) from its red (PrB) to farred (PfrB) form leading to its translocation from the cytoplasm to the nucleus to promote gene transcription. (b) Gene expression based on light‐dependent protein degradation. The b‐ZIP transcription factor HY5 is rapidly turned over by the COP1‐dependent proteolysis system in the dark, but white light induces the translocation of COP1 from the nucleus to the cytoplasm while blue light alters COP1 function in a CRY‐dependent fashion, leading to the inactivation of COP1 and thus the stabilization of HY5 that triggers the transcription of light‐induced genes.



Anthony RG, Henriques R, Helfer A et al. (2004) A protein kinase target of a PDK1 signalling pathway is involved in root hair growth in Arabidopsis. The EMBO Journal 23: 572–581.

Barabasi AL and Oltvai ZN (2004) Network biology: understanding the cell's functional organization. Nature Reviews Genetics 5: 101–113.

Bothwell JH and Ng CK (2005) The evolution of Ca2+ signalling in photosynthetic eukaryotes. New Phytologist 166: 21–38.

Braam J and Davis RW (1990) Rain‐, wind‐, and touch‐induced expression of calmodulin and calmodulin‐related genes in Arabidopsis. Cell 60: 357–364.

Colby T, Matthai A, Boeckelmann A and Stuible HP (2006) SUMO‐conjugating and SUMO‐deconjugating enzymes from Arabidopsis. Plant Physiology 142: 318–332.

Devoto A Nieto‐Rostro M, Xie D et al. (2002) COI1 links jasmonate signalling and fertility to the SCF ubiquitin–ligase complex in Arabidopsis. The Plant Journal 32: 457–466.

Harper JF andHarmon A (2005) Plants, symbiosis and parasites: a calcium signalling connection. Nature Reviews Molecular Cell Biology 6: 555–566.

Ingram GC (2005) Plant development: spacing out stomatal pores. Current Biology 15: R663–R665.

Ito Y, Nakanomyo I, Motose H et al. (2006) Dodeca‐CLE peptides as suppressors of plant stem cell differentiation. Science 313: 842–845.

Lechner E, Achard P, Vansiri A, Potuschak T and Genschik P (2006) F‐box proteins everywhere. Current Opinion in Plant Biology 9: 631–638.

van Leeuwen W, Okresz L, Bogre L et al. (2004) Learning the lipid language of plant signalling. Trends in Plant Science 9: 378–384.

Leyser O (2006) Dynamic integration of auxin transport and signalling. Current Biology 16: R424–R433.

Mackintosh C (2004) Dynamic interactions between 14‐3‐3 proteins and phosphoproteins regulate diverse cellular processes. The Biochemical Journal 381: 329–342.

MAPK‐Group (2002) Mitogen‐activated protein kinase cascades in plants: a new nomenclature. Trends in Plant Science 7: 301–308.

Morillo SA and Tax FE (2006) Functional analysis of receptor‐like kinases in monocots and dicots. Current Opinion in Plant Biology 9: 460–469.

Quail PH (2002) Phytochrome photosensory signalling networks. Nature Reviews Molecular Cell Biology 3: 85–93.

Razem FA, El‐Kereamy A, Abrams SR et al. (2006) The RNA‐binding protein FCA is an abscisic acid receptor. Nature 439: 290–294.

Schweighofer A, Hirt H and Meskiene I (2004) Plant PP2C phosphatases: emerging functions in stress signaling. Trends in Plant Science 9: 236–243.

Shen YY, Wang XF, Wu FQ et al. (2006) The Mg‐chelatase H subunit is an abscisic acid receptor. Nature 443: 823–826.

Stacey G, Libault M, Brechenmacher L et al. (2006) Genetics and functional genomics of legume nodulation. Current Opinion in Plant Biology 9: 110–121.

Ueguchi‐Tanaka M, Ashikari M, Nakajima M et al. (2005) GIBBERELLIN INSENSITIVE DWARF1 encodes a soluble receptor for gibberellin. Nature 437: 693–698.

Further Reading

Bishopp A, Mahonen AP and Helariutta Y (2006) Signs of change: hormone receptors that regulate plant development. Development 133: 1857–1869.

Bogre L, Okresz L, Henriques R et al. (2003) Growth signalling pathways in Arabidopsis and the AGC protein kinases. Trends in Plant Science 8: 424–431.

Johnson KL and Ingram GC (2005) Sending the right signals: regulating receptor kinase activity. Current Opinion in Plant Biology 8: 648–656.

Jonak C, Okresz L, Bogre L et al. (2002) Complexity, cross talk and integration of plant MAP kinase signalling. Current Opinion in Plant Biology 5: 415–424.

Jones AM and Assmann SM (2004) Plants: the latest model system for G‐protein research. EMBO Reports 5: 572–578.

Hetherington AM and Brownlee C (2004) The generation of Ca(2+) signals in plants. Annual Review of Plant Biology 55: 401–427.

Hwang I, Chen HC and Sheen J (2002) Two‐component signal transduction pathways in Arabidopsis. Plant Physiology 129: 500–515.

Matsubayashi Y and Sakagami Y (2006) Peptide hormones in plants. Annual Review of Plant Biology 57: 649–674.

Maughan SC, Murray JA and Bogre L (2006) A greenprint for growth: signalling the pattern of proliferation. Current Opinion in Plant Biology 9: 490–495.

Meijer HJ and Munnik T (2003) Phospholipid‐based signaling in plants. Annual Review of Plant Biology 54: 265–306.

Nibau C, Wu HM and Cheung AY (2006) RAC/ROP GTPases: ‘hubs’ for signal integration and diversification in plants. Trends in Plant Science 11: 309–315.

Seet BT, Dikic I, Zhou MM et al. (2006) Reading protein modifications with interaction domains. Nature Reviews Molecular Cell Biology 7: 473–483.

Sullivan JA, Shirasu K and Deng XW (2003) The diverse roles of Ubiquitin and the 26S proteasome in the life of plants. Nature Reviews Genetics 4: 948–958.

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Bögre, László(Jul 2007) Cell Signalling Mechanisms in Plants. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0020134]