The arbuscular mycorrhizal (AM) symbiosis between terrestrial plants and AM fungi is regulated by plant hormones. For most of these, a role has been clearly assigned in this mutualistic interaction; however, there are still contradictory reports for cytokinin (CK). Here, pea plants, the wild type (WT) cv. Sparkle and its mutant E151 (Pssym15), were inoculated with the AM fungus Rhizophagus irregularis. E151 has previously been characterized as possessing high CK levels in non-mycorrhizal (myc-) roots and exhibiting high number of fungal structures in mycorrhizal (myc+) roots. Myc- and myc+ plants were treated 7, 9, and 11 days after inoculation (DAI) with synthetic compounds known to alter CK status. WT plants were treated with a synthetic CK [6-benzylaminopurine (BAP)] or the CK degradation inhibitor INCYDE, whereas E151 plants were treated with the CK receptor antagonist PI-55. At 13 DAI, plant CK content was analyzed by mass spectrometry. The effects of the synthetic compounds on AM colonization were assessed at 28 (WT) or 35 (E151) DAI via a modified magnified intersections method. The only noticeable difference seen between myc- and myc+ plants in terms of CK content was in the levels of nucleotides (NTs). Whereas WT plants responded to fungi by lowering their NT levels, E151 plants did not. Since NTs are thought to be converted into active CK forms, this result suggests that active CKs were synthesized more effectively in WT than in E151. In general, myc+ and myc- WT plants responded similarly to INCYDE by lowering significantly their NT levels and increasing slightly their active CK levels; these responses were less obvious in BAP-treated WT plants. In contrast, the response of E151 plants to PI-55 depended on the plant mycorrhizal status. Whereas treated myc- plants exhibited high NT and low active CK levels, treated myc+ plants displayed low levels of both NTs and active CKs. Moreover, treated WT plants were more colonized than treated E151 plants. We concluded that CKs have a stimulatory role in AM colonization because increased active CK levels were paralleled with increased AM colonization while decreased CK levels corresponded to reduced AM colonization.

Biology Trent University Peterborough ON Canada

Biology Wilfrid Laurier University Waterloo ON Canada

Centre of the Region Haná for Biotechnological and Agricultural Research Palacký University Olomouc Olomouc Czechia

Mycology Applied Microbiology Earth and Life Institute Université catholique de Louvain Louvain la Neuve Belgium

Zobrazit více v PubMed

Adolfsson L., Nziengui H., Abreu I. N., Šimura J., Beebo A., Herdean A., et al. (2017). Enhanced secondary- and hormone metabolism in leaves of arbuscular mycorrhizal PubMed DOI PMC

Akiyama K., Matsuzaki K.-I., Hayashi H. (2005). Plant sesquiterpenes induce hyphal branching in arbuscular mycorrhizal fungi. PubMed DOI

Allen M. F., Moore T. S., Jr., Christensen M. (1980). Phytohormone changes in DOI

Aremu A. O., Stirk W. A., Masondo N. A., Plačkova L., Novák O., Pěnčik A., et al. (2015). Dissecting the role of two cytokinin analogues (INCYDE and PI-55) on PubMed DOI

Ariel F., Brault-Hernandez M., Laffont C., Huault E., Brault M., Plet J., et al. (2012). Two direct targets of cytokinin signaling regulate symbiotic nodulation in PubMed DOI PMC

Audet P., Charest C. (2010). Identification of constraining experimental-design factors in mycorrhizal pot-growth studies. DOI

Baas R., Kuiper D. (1989). Effects of vesicular-arbuscular mycorrhizal infection and phosphate on DOI

Bedini A., Mercy L., Schneider C., Franken P., Lucic-Mercy E. (2018). Unraveling the initial plant hormone signaling, metabolic mechanisms and plant defense triggering the endomycorrhizal symbiosis behavior. PubMed DOI PMC

Bompadre M. J., Fernández Bidondo L., Silvani V. A., Colombo R. P., Pérgola M., Pardo A. G., et al. (2015). Combined effects of arbuscular mycorrhizal fungi and exogenous cytokinins on pomegranate ( DOI

Bravo A., Brands M., Wewer V., Dörmann P., Harrison M. J. (2017). Arbuscular mycorrhiza-specific enzymes FatM and RAM2 fine-tune lipid biosynthesis to promote development of arbuscular mycorrhiza. PubMed DOI

Bucher M., Hause B., Krajinski F., Küster H. (2014). Through the doors of perception to function in arbuscular mycorrhizal symbioses. PubMed DOI

Coba de la Peña T., Cárcamo C. B., Almonacid L., Zaballos A., Lucas M. M., Balemenos D., et al. (2008). A cytokinin receptor homologue is induced during root nodule organogenesis and senescence in PubMed DOI

Cosme M., Ramireddy E., Franken P., Schmülling T., Wurst S. (2016). Shoot and root-borne cytokinin influences arbuscular mycorrhizal symbiosis. PubMed DOI PMC

Cosme M., Wurst S. (2013). Interactions between arbuscular mycorrhizal fungi, rhizobacteria, soil phosphorus and plant cytokinin deficiency change the root morphology, yield and quality of tobacco. DOI

Danneberg G., Latus C., Zimmer W., Hundeshagen B., Schneider-Poetsch H., Bothe H. (1992). Influence of vesicular-arbuscular mycorrhiza on phytohormones balances in maize ( DOI

Das D., Gutjahr C. (2019). “Role of phytohormones in arbuscular mycorrhiza development. Chapter 7” in

Declerck S., Strullu D. G., Plenchette C. (1998). Monoxenic culture of the intraradical forms of Glomus sp. isolated from a tropical ecosystem: a proposed methodology for germplasm collection. DOI

Dickson S., Smith F. A., Smith S. E. (2007). Structural differences in arbuscular mycorrhizal symbioses; more than 100 years after gallaud, where next? PubMed DOI

Dixon R. K., Garrett H. E., Cox G. S. (1988). Cytokinins in the root pressure exudate of PubMed DOI

Drüge U., Schönbeck F. (1992). Effect of vesicular-arbuscular mycorrhizal infection on transpiration, photosynthesis and growth of flax ( DOI

Farrow S. C., Emery R. J. N. (2012). Concurrent profiling of indole-3-acetic acid, abscisic acid, and cytokinins and structurally related purines by high-performance-liquid-chromatography tandem electrospray mass spectrometry. PubMed DOI PMC

Foo E., Ross J. J., Jones W. T., Reid J. B. (2013). Plant hormones in arbuscular mycorrhizal symbioses: an emerging role for gibberellins. PubMed DOI PMC

Franson R. L., Bethlenfalvay G. J. (1989). Infection unit method of vesicular-arbuscular mycorrhizal propagules determination. DOI

Fusconi A. (2014). Regulation of root morphogenesis in arbuscular mycorrhizae: what role do fungal exudates, phosphate, sugars and hormones play in lateral root formation? PubMed DOI PMC

Gaude N., Bortfeld S., Duensing N., Lohse M., Krajinski F. (2012). Arbuscule-containing and non-colonized cortical cells of mycorrhizal roots undergo extensive and specific reprogramming during arbuscular mycorrhizal development. PubMed DOI

Ginzberg I., David R., Shaul O., Elad Y., Wininger S., Ben-Dor B., et al. (1998).

Giovannetti M., Mosse B. (1980). An evaluation of techniques for measuring vesicular arbuscular mycorrhizal infection in roots. DOI

Glenn M. G., Chew F. S., Williams P. H. (1985). Hyphal penetration of DOI

Goicoechea N., Dolézal K., Antolin M. C., Strnad M., Sánchez-Diaz M. (1995). Influence of mycorrhiza and DOI

Gonzalez-Rizzo S., Crespi M., Frugier F. (2006). The PubMed DOI PMC

Gryndler M., Hršelová H., Chvátalová I., Jansa J. (1998). The effect of selected plant hormones on in vitro proliferation of hyphae of DOI

Guether M., Neuhaüser B., Balestrini R., Dynowski M., Ludewig U., Bonfante P. (2009). A mycorrhizal-specific ammonium transporter from PubMed DOI PMC

Gutjahr C. (2014). Phytohormone signaling in arbuscular mycorrhiza development. PubMed DOI

Harrison M. J., Dewbre G. R., Liu J. (2002). A phosphate transporter from PubMed DOI PMC

Helber N., Wippel K., Sauer N., Schaarschmidt S., Hause B., Requena N. (2011). A versatile monosaccharide transporter that operates in the arbuscular mycorrhizal fungus PubMed DOI PMC

Held M., Hou H., Miri M., Huynh C., Ross L., Hossain M. S., et al. (2014). PubMed DOI PMC

Higuchi M., Pischke M. S., Mähönen A. P., Miyawaki K., Hashimoto Y., Seki M., et al. (2004). In planta functions of the PubMed DOI PMC

Jardinaud M.-F., Boivin S., Rodde N., Catrice O., Kisiala A., Lepage A., et al. (2016). A laser dissection-RNAseq analysis highlights the activation of cytokinin pathways by nod factors in the PubMed DOI PMC

Jones J. M. C., Clairmont L., Macdonald E. S., Weiner C. A., Emery R. J. N., Guinel F. C. (2015). E151 (sym15), a pleiotropic mutant of pea ( PubMed DOI PMC

Kieber J. J., Schaller G. E. (2010). The perception of cytokinin: a story 50 years in the making. PubMed DOI PMC

Kneen B. E., Weeden N. F., LaRue T. A. (1994). Non-nodulating mutants of DOI

Knott C. M. (1987). A key for stages of development of the pea ( DOI

Ko D., Kang J., Kiba T., Park J., Kojima M., Do J., et al. (2014). PubMed DOI PMC

Lace B., Ott T. (2018). Commonalities and differences in controlling multipartite intracellular infections of legume roots by symbiotic microbes. PubMed DOI

Laffont C., Rey T., André O., Novero M., Kazmierczak T., Debellé F., et al. (2015). The CRE1 cytokinin pathway is differentially recruited depending on PubMed DOI PMC

Liao D., Wang S., Cui M., Liu J., Chen A., Xu G. (2018). Phytohormones regulate the development of arbuscular mycorrhizal symbiosis. PubMed DOI PMC

Lomin S. N., Myakushina Y. A., Kolachevskaya O. O., Getman I. A., Arkhipov D. V., Savelleva E. M., et al. (2018). Cytokinin perception in potato: new features of canonical players. PubMed DOI PMC

Long C., Held M., Hayward A., Nisler J., Spíchal L., Emery R. J. N., et al. (2012). Seed development, seed germination and seedling growth in the R50 (sym16) pea mutant are not directly linked to altered cytokinin homeostasis. PubMed DOI

MacColl K. (2017).

McGonigle T. P., Miller M. H., Evans D. G., Fairchild G. L., Swan J. A. (1990). A new method which gives an objective measure of colonization of roots by vesicular-arbuscular mycorrhizal fungi. PubMed DOI

Murray J. D., Karas B. J., Sato S., Tabata S., Amyot L., Szczyglowski K. (2007). A cytokinin perception mutant colonized by PubMed DOI

Plet J., Wasson A., Ariel F., Le Signor C., Baker D., Mathesius U., et al. (2011). MtCRE1-dependent cytokinin signaling integrates bacterial and plant cues to coordinate symbiotic nodule organogenesis in PubMed DOI

Pozo M. J., López-Ráez J. A., Azcón-Aguilar C., García-Garrido J. M. (2015). Phytohormones as integrators of environmental signals in the regulation of mycorrhizal symbioses. PubMed DOI

Quesnelle P. E., Emery R. J. N. (2007). Cis-cytokinins that predominate DOI

R Core Team. (2017).

Rausch C., Daram P., Brunner S., Jansa J., Laloi M., Leggewie G., et al. (2001). A phosphate transporter expressed in arbuscule-containing cells in potato. PubMed DOI

Resendes C. M., Geil R. D., Guinel F. C. (2001). Mycorrhizal development in a low nodulating pea mutant. DOI

Riefler M., Novak O., Strnad M., Schmülling T. (2006). PubMed DOI PMC

Romanov G. A., Lomin S. N., Schmülling T. (2006). Biochemical characteristics and ligand-binding properties of PubMed DOI

Sakakibara H. (2006). Cytokinins: activity, biosynthesis, and translocation. PubMed DOI

Schmidt C. S., Mrnka L., Frantik T., Motyka V., Dobrev P. I., Vosátka M. (2017). Combined effects of fungal inoculants and the cytokinin-like growth regulator thidiazuron on growth, phytohormone contents and endophytic root fungi in PubMed DOI

Shaul-Keinan O., Gadkar V., Ginzberg I., Grünzweig J. M., Chet I., Elad Y., et al. (2002). Hormone concentrations in tobacco roots change during arbuscular mycorrhizal colonization with PubMed DOI

Skalický V., Kubeš M., Napier R., Novák O. (2018). Auxins and cytokinins–The role of subcellular organization on homeostasis. PubMed DOI PMC

Smith S. E., Read D. J. (2008).

Spíchal L. (2012). Cytokinins – recent news and views of evolutionally old molecules. PubMed DOI

Spíchal L., Rakova N. Y., Riefler M., Mizuno T., Romanov G. A., Strnad M., et al. (2004). Two cytokinin receptors of PubMed DOI

Spíchal L., Werner T., Popa I., Riefler M., Schmülling T., Strnad M. (2009). The purine derivative PI-55 blocks cytokinin action via receptor inhibition. PubMed DOI

Torelli A., Trotta A., Acerbi L., Arcidiacono G., Berta G., Branca C. (2000). IAA and ZR content in leek ( DOI

van Rhijn P., Fang Y., Galili S., Shaul O., Atzmon N., Wininger S., et al. (1997). Expression of early nodulin genes in alfalfa mycorrhizae indicates that signal transduction pathways used in forming arbuscular mycorrhizae and PubMed DOI PMC

Vierheilig H., Coughlan A. P., Wyss U., Piché Y. (1998). Ink and vinegar, a simple staining technique for arbuscular-mycorrhizal fungi. PubMed PMC

Werner T., Schmülling Y. (2009). Cytokinin action in plant development. PubMed DOI

Yurkov A., Veselova S., Jacobi L., Stepanova G., Yemelyanov V., Kudoyarova G., et al. (2017). The effect of inoculation with arbuscular mycorrhizal fungus DOI

Zatloukal M., Gemrotová M., Doležal K., Havlíček L., Spíchal L., Strnad M. (2008). Novel potent inhibitors of PubMed DOI

Zhang K., Novak O., Wei Z., Gou M., Zhang X., Yu Y., et al. (2014). PubMed DOI

Soil nutrient status of KwaZulu-Natal savanna and grassland biomes causes variation in cytokinin functional groups and their levels in above-ground and underground parts of three legumes

Targeting Cytokinin Homeostasis in Rapid Cycling Brassica rapa with Plant Growth Regulators INCYDE and TD-K

Cytokinin and Ethylene Cell Signaling Pathways from Prokaryotes to Eukaryotes