It has been recognized that cytokinins are plant hormones that influence not only numerous aspects of plant growth, development and physiology, including cell division, chloroplast differentiation and delay of senescence but the interaction with other organisms, including pathogens. Cytokinins are not only produced by plants but are also by other prokaryotic and eukaryotic organism such as bacteria, fungi, microalgae and insects. Notably, cytokinins are produced both by pathogenic and also beneficial microbes and are known to induce resistance in plants against pathogen infections. In this review the contrasting role of cytokinin for the defence and susceptibility of plants against bacterial and fungal pathogen and pest insects is assessed. We also discuss the cross talk of cytokinins with other phytohormones and the underlying mechanism involved in enhancing plant immunity against pathogen infections and explore possible practical applications in crop plant production.

Department of Adaptive Biotechnologies Global Change Research Institute CAS Brno Czechia

Department of Plant and Environmental Sciences University of Copenhagen Copenhagen Denmark

Zobrazit více v PubMed

Akagi A., Fukushima S., Okada K., Jiang C. J., Yoshida R., Nakayama A., et al. (2014). WRKY45-dependent priming of diterpenoid phytoalexin biosynthesis in rice and the role of cytokinin in trig- gering the reaction. Plant Mol. Biol. 86, 171–183. 10.1007/s11103-014-0221-x PubMed DOI PMC

Akhtar S. S., Andersen M. N., Naveed M., Zahir Z. A., Liu F. (2015). Interactive effect of biochar and plant growth-promoting bacterial endophytes on ameliorating salinity stress in maize. Funct. Plant Biol. 4, 770–781. 10.1071/Fp15054 PubMed DOI

Albrecht T., Argueso C. T. (2017). Should I fight or should I grow now? the role of cytokinins in plant growth and immunity and in the growth-defence trade-off. Ann. Bot. 119, 725–735. 10.1093/aob/mcw211 PubMed DOI PMC

Angra-Sharma R., Sharma D. K. (2000). Cytokinins in pathogenesis and disease resistance of Pyrenophora teres-barley and Dreschslera maydis-maize interactions during early stages of infection. Mycopathologia 148, 87–95. 10.1023/a:1007126025955 PubMed DOI

Argueso C. T., Ferreira F. J., Epple P., To J. P., Hutchison C. E., Schaller G. E., et al. (2012). Two-component elements mediate interactions between cytokinin and salicylic acid in plant immunity. PLoS Genet. 8, e1002448. 10.1371/journal.pgen.1002448 PubMed DOI PMC

Arkhipova T. N., Veselov S. U., Melentiev A. I., Martynenko E. V., Kudoyarova G. R. (2005). Ability of bacterium Bacillus subtilis to produce cytokinins and to influence the growth and endogenous hormone content of lettuce plants. Plant Soil 272, 201–209. 10.1007/s11104-004-5047-x DOI

Arkhipova T. N., Prinsen E., Veselov S. U., Martinenko E. V., Melentiev A. I., Kudoyarova G. R. (2007). Cytokinin producing bacteria enhance plant growth in drying soil. Plant Soil 292, 305–315. 10.1007/s11104-007-9233-5 DOI

Babosha A. V. (2009). Regulation of resistance and susceptibility in wheat- powdery mildew pathosystem with exogenous cytokinins. J. Plant Physiol. 166, 1892–1903. 10.1371/journal.pgen.1002448 PubMed DOI

Babu S., Bidyarani N., Chopra P., Monga D., Kumar R., Prasanna R., et al. (2015). Evaluating microbe-plant interactions and varietal differences for enhancing biocontrol efficacy in root rot disease challenged cotton crop. Eur. J. Plant Pathol. 142, 345–362. 10.1007/s10658-015-0619-6 DOI

Belimov A. A., Dodd I. C., Safronova V. I., Shaposhnikov A. I., Azarova T. S., Makarova N. M., et al. (2015). Rhizobacteria that produce auxins and contain 1-amino-cyclopropane-1-carboxylic acid deaminase decrease amino acid concentrations in the rhizosphere and improve growth and yield of well-watered and water-limited potato (Solanum tuberosum). Ann. App. Biol. 167, 11–25. 10.1111/aab.12203 DOI

Bennett E., Roberts J. A., Wagstaff C. (2012). Manipulating resource allocation in plants. J. Exp. Bot. 63, 3391–3400. 10.1093/jxb/err442 PubMed DOI

Berens M. L., Berry H. M., Mine A., Argueso C. T., Tsuda K. (2017). Evolution of hormone signaling networks in plant defense. Ann. Rev. Phytopathol. 55, 401–425. 10.1146/annurev-phyto-080516-035544 PubMed DOI

Berger S., Sinha A. K., Roitsch T. (2007). Plant physiology meets phytopathology: plant primary metabolism and plant-pathogen interactions. J. Expt. Bot. 58, 4019–4026. 10.1093/jxb/erm298 PubMed DOI

Brütting C., Crava C. M., Schäfer M., Schuman M. C., Meldau S., Adam N., et al. (2018). Cytokinin transfer by a free-living mirid to Nicotiana attenuata recapitulates a strategy of endophytic insects. Elife 7, e36268. 10.7554/eLife.36268 PubMed DOI PMC

Castillo P., Molina R., Andrade A., Vigliocco A., Alemano S., Cassán F. D. (2015). “Phytohormones and other plant growth regulators produced by PGPR: The genus Azospirillum ,” in Handbook for Azospirillum. Eds. Cassán F., Okon Y., Creus C. (Cham: Springer; ). 10.1007/978-3-319-06542-7_7 DOI

Chanclud E., Kisiala A., Emery N. R., Chalvon V., Ducasse A., Romiti-Michel C., et al. (2016). Cytokinin production by the rice blast fungus is a pivotal requirement for full virulence. PLoS Pathog. 12, e1005457. 10.1371/journal.ppat.1005457 PubMed DOI PMC

Choi J., Hwang I. (2007). Cytokinin: perception, signal transduction, and role in plant growth and development. J. Plant Biol. 50, 98–108. 10.1007/BF03030617 DOI

Choi J., Huh S. U., Kojima M., Sakakibara H., Paek K. H., Hwang I. (2010). The Cytokinin-activated transcription factor ARR2 promotes plant immunity via TGA3/NPR1-dependent salicylic acid signaling in arabidopsis. Dev. Cell 19, 284–295. 10.1016/j.devcel.2010.07.011 PubMed DOI

Chowdhury M. M. H., Kubra K., Hossain M. B., Mustafa M. G., Jainab T., Karim M. R., et al. (2015). Screening of antibacterial and antifungal activity of freshwater and marine algae as a prominent natural antibiotic available in Bangladesh. Int. J. Pharmacol. 11, 828–833. 10.3923/ijp.2015.828.833 DOI

Cordero I., Balaguer L., Rincon A., Pueyo J. J. (2018). Inoculation of tomato plants with selected PGPR represents a feasible alternative to chemical fertilization under salt stress. J. Plant Nut. Soil Sci. 181, 694–703. 10.1002/jpln.201700480 DOI

Cortleven A., Leuendorf J. E., Frank M., Pezzetta D., Bolt S., Schmulling T. (2019). Cytokinin action in response to abiotic and biotic stresses in plants. Plant Cell Environ. 42, 998–1018. 10.1111/pce.13494 PubMed DOI

Craft C. A., Hiltz D. A., Hankins S. D., MacKinnon S. L. (2007). Detection of plant growth hormones in Ascophyllum nodosum and seaweed products, in: MANAPRO XII, Proceedings of the 12th International Symposium on Marine Natural Products in Queenstown New Zealand, Oral-Poster Abstract, PO74-OR, 2007.

Davies P. J. (2010). “The plant hormones: their nature, occurrence, and functions,” in Plant hormones. Ed. Davies P. J. (Dordrecht: Springer; ), 1–15.

Dermastia M. (2019). Plant hormones in phytoplasma infected plants. Front. Plant Sci. 10, 477. 10.3389/fpls.2019.00477 PubMed DOI PMC

Dervinis C., Frost C. J., Lawrence S. D., Novak N. G., Davis J. M. (2010). Cytokinin primes plant responses to wounding and reduces insect performance. J. Plant Growth Regul. 29, 289–296. 10.1007/s00344-009-9135-2 DOI

Dowd C. D., Chronis D., Radakovic Z. S., Siddique S., Schmülling T., Werner T., et al. (2017). Divergent expression of cytokinin biosynthesis, signaling and catabolism genes underlying differences in feeding sites induced by cyst and root-knot nematodes. Plant J. 92, 211–228. 10.1111/tpj.13647 PubMed DOI

Dukare A. S., Prasanna R., Dubey S. C., Chaudhary V., Nain L., Singh R., et al. (2011). Evaluating novel microbe amended composts as biocontrol agents in tomato. Crop Prot. 30, 436–442. 10.1016/j.cropro.2010.12.017 DOI

Egamberdieva D., Wirth S. J., Alqarawi A. A., Abd_Allah E. F., Hashem A. (2017). Phytohormones and beneficial microbes: essential components for plants to balance stress and fitness. Front. Microbiol. 8, 1–14. 10.3389/fmicb.2017.02104 PubMed DOI PMC

Ehneß R., Roitsch T. (1997). Coordinated induction of extracellular invertase and glucose transporters in Chenopodium rubrum by cytokinins. Plant J. 11, 539–548. 10.1046/j.1365-313x.1997.11030539.x PubMed DOI

Elzen G. W. (1983). Minireview: cytokinins and insect galls. Comp. Bioch. Physiol. 76, 17–19. 10.1016/0300-9629(83)90286-4 DOI

Engelbrecht L., Orban U., Heese W. (1969). Leaf-miner caterpillars and cytokinins in the “green islands” of autumn leaves. Nature 223, 319. 10.1038/223319a0 DOI

Galal H. R. M., Salem W. M., Nasr El-Deen F. (2011). Biological control of some pathogenic fungi using marine algae. Res. J. Microbiol. 6, 645–657. 10.3923/jm.2011.645.657 DOI

Giron D., Glevarec G. (2014). Cytokinin-induced phenotypes in plant-insect interactions: learning from the bacterial. World J. Chem. Ecol. 40, 826–835. 10.1007/s10886-014-0466-5 PubMed DOI

Giron D., Kaiser W., Imbault N., Casas J. (2007). Cytokinin-mediated leaf manipulation by a leafminer caterpillar. Biol. Lett. 3, 340–343. 10.1098/rsbl.2007.0051 PubMed DOI PMC

Giron D., Frago E., Glevarec G., Pieterse C. M., Dicke M. (2013). Cytokinins as key regulators in plant–microbe–insect interactions: connecting plant growth and defence. Funct. Ecol. 27, 599–609. 10.1111/1365-2435.12042 DOI

Giron D., Huguet E., Stone G. N., Body M. (2016). Insect-induced effects on plants and possible effectors used by galling and leaf-mining insects to manipulate their host-plant. J. Insect Physiol. 84, 70–89. 10.1016/j.jinsphys.2015.12.009 PubMed DOI

Glick B. R., Bashan Y. (1997). Genetic manipulation of plant growth-promoting bacteria to enhance biocontrol of phytopathogens. Biotech. Adv. 15, 353–378. 10.1016/S0734-9750(97)00004-9 PubMed DOI

Großkinsky D. K., Syaifullah S. J., Roitsch T. (2017). Integration of multi-omics techniques and physiological phenotyping within a holistic phenomics approach to study senescence in model and crop plants. J. Exp. Bot. 66, 825–844. 10.1093/jxb/erx333 PubMed DOI

Grosskinsky D. K., Naseem M., Abdelmohsen U. R., Plickert N., Engelke T., Griebel T., et al. (2011). Cytokinins mediate resistance against Pseudomonas syringae in tobacco through increased antimicrobial phytoalexin synthesis independent of salicylic acid signaling. Plant Physiol. 157, 815–830. 10.1104/pp.111.182931 PubMed DOI PMC

Grosskinsky D. B., Edelsbrunner K., Pfeifhofer H., v. d. Graaff E., Roitsch T. (2013). Cis- and trans-zeatin differentially modulate plant immunity. Plant Signal. Behav. 8:7, e24798. 10.4161/psb.24798 PubMed DOI PMC

Grosskinsky D. K., Tafner R., Moreno M. V., Stenglein S. A., de Salamone I. E. G., Nelson L. M., et al. (2016). Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis. Sci. Rep. 6, 23310. 10.1038/srep23310 PubMed DOI PMC

Guo Y., Gan S. (2014). Translational researches of leaf senescence for enhancing plant productivity and quality. J. Exp. Bot. 65, 3901–3913. 10.1093/jxb/eru248 PubMed DOI

Gururani M. A., Upadhyaya C. P., Baskar V., Venkatesh J., Nookaraju A., Park S. W. (2013). Plant growth-promoting rhizobacteria enhance abiotic atress tolerance in Solanum tuberosum through inducing changes in the expression of ROS-Scavenging enzymes and improved photosynthetic performance. J. Plant Growth Regul. 32, 245–258. 10.1007/s00344-012-9292-6 DOI

Hinsch J., Vrabka J., Oeser B., Novák O., Galuszka P., Tudzynski P. (2015). De novo biosynthesis of cytokinins in the biotrophic fungus Claviceps purpurea . Environ. Microbiol. 17, 2935–2951. 10.1111/1462-2920.12838 PubMed DOI

Holland M. A. (1997). Occam's razor applied to hormonology. Plant Physiol. 115, 865–868. 10.1104/pp.115.3.865 PubMed DOI PMC

Hui D., Iqbal J., Lehmann K., Gase K., Saluz H. P., Baldwin I. T. (2003). Molecular Interactions between the specialist herbivoremanduca sexta (Lepidoptera, Sphingidae) and its natural host nicotiana attenuata: V. Microarray analysis and further characterization of large-scale changes in herbivore-induced mRNAs. Plant Physiol. 131, 1877–1893. 10.1104/pp.102.018184 PubMed DOI PMC

Hussain A., Krischke M., Roitsch T., Hasnain S. (2010). Rapid determination of cytokinins and auxin in cyanobacteria. Curr. Microbiol. 6, 361–369. 10.1007/s00284-010-9620-7 PubMed DOI

Hwang H. H., Wang M. H., Lee Y. L., Tsai Y. L., Li Y. H., Yang F. J., et al. (2010). Agrobacterium-produced and exogenous cytokinin-modulated Agrobacterium-mediated plant transformation. Mol. Plant Pathol. 11, 677–690. 10.1111/j.1364-3703.2010.00637.x PubMed DOI PMC

Hwang I., Sheen J., Müller B. (2012). Cytokinin signaling networks. Annu. Rev. Plant Biol. 63, 353–380. 10.1146/annurev-arplant-042811-105503 PubMed DOI

Ishizawa H., Kuroda M., Inoue K., Inoue D., Morikawa M., Ike M. (2019). Colonization and competition dynamics of plant growth-promoting/inhibiting bacteria in the phytosphere of the duckweed lemna minor. Microb. Ecol. 77, 440–450. 10.1007/s00248-018-1306-x PubMed DOI

Jameson P. E., Dhandapani P., Song J., Zatloukal M., Strnad M., Remus-Emsermann M. N., et al. (2019). The cytokinin complex associated with Rhodococcus fascians: which compounds are critical for virulence? Front. Plant Sci. 10, 674. 10.3389/fpls.2019.00674 PubMed DOI PMC

Jameson P. E. (2000). Cytokinins and Auxins in plant-pathogen interactions - an overview. Plant Growth Regul. 32, 369–380. 10.1023/A:1010733617543 DOI

Jaulneau V., Lafitte C., Jacquet C., Fournier S., Salamagne S., Briand X., et al. (2010). Ulvan, a sulfated polysaccharide from green algae, activates plant immunity through the jasmonic acid signaling pathway. J. Biomed. Biotechnol. 2010, 525291. 10.1155/2010/525291 PubMed DOI PMC

Jiang C.-J., Shimono M., Sugano S., Kojima M., Liu X., Inoue H., et al. (2013). Cytokinins act synergistically with salicylic acid to activate defense gene expression in rice. Mol. Plant. Microbe Interact. 26, 287–296. 10.1094/MPMI-06-12-0152-R PubMed DOI

Jorge G. L., Kisiala A., Morrison E., Aoki M., Nogueira A. P. O., Emery R. J. N. (2019). Endosymbiotic Methylobacterium oryzae mitigates the impact of limited water availability in lentil (Lens culinaris Medik.) by increasing plant cytokinin levels. Env. Exp. Bot. 162, 525–540. 10.1016/j.envexpbot.2019.03.028 DOI

Joseph J., Kieber G., Schaller E. (2018). Cytokinin signaling in plant development. Development 145, dev149344. 10.1242/dev.149344 PubMed DOI

Kaiser W., Huguet E., Casas J., Commin C., Giron D. (2010). Plant green-island phenotype induced by leaf-miners is mediated by bacterial symbionts. Proc. Royal Soc. B. Biol. Sci. 277, 2311–2319. 10.1098/rspb.2010.0214 PubMed DOI PMC

Kaminek M. (2015). Tracking the story of cytokinin research. J. Plant Growth Regul. 34, 723–739. 10.1007/s00344-015-9543-4 DOI

Kanwal S., Ilyas N., Batool N., Arshad M. (2017). Amelioration of drought stress in wheat by combined application of PGPR, compost, and mineral fertilizer. J. Plant Nutr. 40, 1250–1260. 10.1080/01904167.2016.1263322 DOI

Kind S., Hinsch J., Vrabka J., Hradilová M., Majeská-Čudejková M., Tudzynski P., Galuszka P. (2018). Manipulation of cytokinin level in the ergot fungus Claviceps purpurea emphasizes its contribution to virulence. Curr. Gent. 64, 1303–1319. 10.1007/s00294-018-0847-3 PubMed DOI

Kumar M., Kour D., Yadav A. N., Saxena R., Rai P. K., Jyoti A., et al. (2019). Biodiversity of methylotrophic microbial communities and their potential role in mitigation of abiotic stresses in plants. Biologia 74, 287–308. 10.2478/s11756-019-00190-6 DOI

Lara M. E. B., Garcia M. C. G., Fatima T., Ehneß R., Lee T. K., Proels R., et al. (2004). Extracellular invertase is an essential component of cytokinin-mediated delay of senescence. Plant Cell 16, 1276–1287. 10.1105/tpc.018929 PubMed DOI PMC

Lisabeth E. (1971). Cytokinin activity in larval infected leaves. Biochem. Physiol. Pflanz. 162, 9–27. 10.1016/S0015-3796(17)31102-2 DOI

Liu F. C., Xing S. J., Ma H. L., Du Z. Y., Ma B. Y. (2013). Cytokinin-producing, plant growth-promoting rhizobacteria that confer resistance to drought stress in Platycladus orientalis container seedlings. App. Microb. Biotech. 97, 9155–9164. 10.1007/s00253-013-5193-2 PubMed DOI

Liu Z., Bushnell W. R. (1986). Effects of cytokinins on fungus development and host response in powdery mildew of barley. Physiol. Mol. Plant Pathol. 29 (1), 47–52. 10.1016/S0048-4059(86)80036-4 DOI

Maheshwari D. K., Dheeman S., Agarwal M. (2015). “Phytohormone-producing PGPR for sustainable sgriculture,” in Bacterial Metabolites in Sustainable Agroecosystem. Sustainable Development and Biodiversity, vol. 12 Ed. Maheshwari D. (Cham: Springer; ), 159–182. 10.1007/978-3-319-24654-3_7 DOI

Maksimov I. V., Abizgil'dina R. R., Pusenkova L. I. (2011). Plant growth promoting rhizobacteria as alternative to chemical crop protectors from pathogens (review). Appl. Biochem. Micro. 47, 333–345. 10.1134/S0003683811040090 PubMed DOI

Mapes C. C., Davies P. J. (2001). Cytokinins in the ball gall of Solidago altissima and in the gall forming larvae of Eurosta solidaginis. New Phytol. 151, 203–212. 10.1046/j.1469-8137.2001.00158.x PubMed DOI

Mishra V., Ellouze W., Howard R. J. (2018). Utility of Arbuscular Mycorrhizal fungi for improved production and disease mitigation in organic and hydroponic greenhouse crops. J. Hortic. 5, 2376–0354. 10.4172/2376-0354.1000237 DOI

Moreno J. E., Ballaré C. L. (2014). Phytochrome regulation of plant immunity in vegetation canopies. J. Chem. Ecol. 40, 848–857. 10.1007/s10886-014-0471-8 PubMed DOI

Morrison E. N., Emery R. N., Saville B. J. (2015). Phytohormone involvement in the Ustilago maydis–Zea mays pathosystem: relationships between abscisic acid and cytokinin levels and strain virulence in infected cob tissue. PloS One 10, e0130945. 10.1371/journal.pone.0130945 PubMed DOI PMC

Munné-Bosch S., Müller M. (2013). Hormonal cross-talk in plant development and stress responses. Front. Plant Sci. 4, 529. 10.3389/fpls.2013.00529 PubMed DOI PMC

Nadeem S. M., Ahmad M., Zahir Z. A., Javaid A., Ashraf M. (2014). The role of mycorrhizae and plant growth promoting rhizobacteria (PGPR) in improving crop productivity under stressful environments. Biotechnol. Adv. 32, 429–448. 10.1016/j.biotechadv.2013.12.005 PubMed DOI

Nadeem S. M., Imran M., Naveed M., Khan M. Y., Ahmad M., Zahir Z. A., et al. (2017). Synergistic use of biochar, compost and plant growth-promoting rhizobacteria for enhancing cucumber growth under water deficit conditions. J. Sci. Food Agric. 97, 5139–5145. 10.1002/jsfa.8393 PubMed DOI

Naseem M., Dandekar T. (2012). The role of auxin-cytokinin antagonism in plant-pathogen interactions. PLoS Pathog. 8, e1003026. 10.1371/journal.ppat.1003026 PubMed DOI PMC

Naseem M., Kaltdorf M., Hussain A., Dandekar T. (2013). The impact of cytokinin on jasmonate-salicylate antagonism in Arabidopsis immunity against infection with Pst DC3000. Plant Signal. Behav. 8, e26791. 10.4161/psb.26791 PubMed DOI PMC

Naseem M., Wolfling M., Dandekar T. (2014). Cytokinins for immunity beyond growth, galls and green islands. Trends Plant Sci. 19, 481–484. 10.1016/j.tplants.2014.04.001 PubMed DOI

Novák J., Pavlů J., Novák O., Nožková-Hlaváčková V., Špundová M., Hlavinka J., et al. (2013). High cytokinin levels induce a hypersensitive-like response in tobacco. Ann. Bot. 112, 41–55. 10.1093/aob/mct092 PubMed DOI PMC

O'Brien J. A., Benková E. (2013). Cytokinin cross-talking during biotic and abiotic stress responses. Front. Plant Sci. 4, 451. 10.3389/fpls.2013.00451 PubMed DOI PMC

Pangesti N., Pineda A., Pieterse C. M., Dicke M., Van-Loon J. J. (2013). Two-way plant mediated interactions between root-associated microbes and insects: from ecology to mechanisms. Front. Plant Sci. 4, 1–11. 10.3389/fpls.2013.00414 PubMed DOI PMC

Pieterse C. M., Zamioudis C., Berendsen R. L., Weller D. M., Van Wees S. C., Bakker P. A. (2014). Induced systemic resistance by beneficial microbes. Ann. Rev. Phytopathol. 52, 347–375. 10.1146/annurev-phyto-082712-102340 PubMed DOI

Pospisilova J., Vagner M., Malbeck J., Travnickova A., Batkova P. (2005). Interactions between abscisic acid and cytokinins during water stress and subsequent rehydration. Biol. Plant. 49, 533–540. 10.1007/s10535-005-0047-0 DOI

Prasanna R., Chaudhary V., Gupta V., Babu S., Kumar A., Singh R., et al. (2013). Cyanobacteria mediated plant growth promotion and bioprotection against Fusarium wilt in tomato. Eu. J. Plant Pathol. 136, 337–353. 10.1007/s10658-013-0167-xs DOI

Pusztahelyi T., Holb I. J., Pócsi I. (2016). “Plant-Fungal Interactions: Special secondary metabolites of the biotrophic, necrotrophic, and other specific interactions,” in Fungal metabolites. Reference Series in Phytochemistry. Eds. Mérillon J. M., Ramawat K. (Cham: Springer; ), 133–190. 10.1007/978-3-319-19456-1_39-1 DOI

Regier D. A., Morris R. O. (1982). Secretion of trans-zeatin by agrobacterium-Tumefaciens - a function determined by the nopaline ti plasmid. Biochem. Biophys. Res. Commun. 104, 1560–1566. 10.1016/0006-291x(82)91429-2 PubMed DOI

Righini H., Roberti R., Baraldi E. (2018). Use of algae in strawberry management. J. Appl. Phycol. 30, 3551–3564. 10.1007/s10811-018-1478-2 DOI

Roitsch T., Ehneß R. (2000). Regulation of source/sink relations by cytokinins. Plant Growth Regul. 32, 359–267. 10.1023/A:1010781500705 DOI

Romanov G. A. (2011). The discovery of cytokinin receptors and biosynthesis of cytokinins: a true story. R. J. Plant Physiol. 58, 743–747. 10.1134/S1021443711040121.pdf DOI

Ryu C. M., Farag M. A., Hu C. H., Reddy M. S., Kloepper J. W., Pare P. W. (2004). Bacterial volatiles induce systemic resistance in Arabidopsis . Plant Physiol. 134, 1017–1026. 10.1104/pp.103.026583 PubMed DOI PMC

Sørensen J. L., Benfield A. H., Wollenberg R. D., Westphal K., Wimmer R., Nielsen M. R., et al. (2018). The cereal pathogen Fusarium pseudograminearum produces a new class of active cytokinins during infection. Mol. Plant Pathol. 19, 1140–1154. 10.1111/mpp.12593 PubMed DOI PMC

Sakakibara H. (2006). Cytokinins: activity, biosynthesis, and translocation. Annu. Rev. Plant Biol. 57, 431–449. 10.1146/annurev.arplant.57.032905.105231 PubMed DOI

Sardesai N., Lee L. Y., Chen H. B., Yi H. C., Olbricht G. R., Stirnberg A., et al. (2013). Cytokinins Secreted by agrobacterium promote transformation by repressing a plant Myb transcription factor. Sci. Signal. 6, ra100. 10.1126/scisignal.2004518 PubMed DOI

Schäfer M., Meza-Canales I. D., Navarro-Quezada A., Brütting C., Vanková R., Baldwin I. T., et al. (2015). Cytokinin levels and signaling respond to wounding and the perception of herbivore elicitors in Nicotiana attenuata. J. Integ. Plant Biol. 57, 198–212. 10.1111/jipb.12227 PubMed DOI PMC

Sekar R., Thangaraju N., Rengasamy R. (1995). Effect of seaweed liquid fertilizer from Ulva lactuca L. on Vigna unguiculata L. (Walp). Phykos 34, 49–53. 10.1007/s10811-017-1082-x DOI

Shanks C. M., Rice J. H., Yan Z. B., Schaller G. E., Hewezi T., Kieber J. J. (2016). The role of cytokinin during infection of Arabidopsis thaliana by the cyst nematode Heterodera schachtii. Mol. Plant-Microbe Interact. 29, 57–68. 10.1094/MPMI-07-15-0156-R PubMed DOI

Siddique S., Radakovic Z. S., Carola M., Chronis D., Novák O., Ramireddy E., et al. (2015). A parasitic nematode releases cytokinin that controls cell division and orchestrates feeding site formation in host plants. Proc. Nat. Acad. Sci. 112, 12669–12674. 10.1073/pnas.1503657112 PubMed DOI PMC

Song J., Jiang L., Jameson P. E. (2015). Expression patterns of Brassica napus genes implicate IPT, CKX, sucrose transporter, cell wall invertase, and amino acid permease gene family members in leaf, flower, silique, and seed development. J. Exp. Botany. 66, 5067–5082. 10.1093/jxb/erv133 PubMed DOI PMC

Spallek T., Melnyk C. W., Wakatake T., Zhang J., Sakamoto Y., Kiba T., et al. (2017). Interspecies hormonal control of host root morphology by parasitic plants. Proc. Nat. Acad. Sci. 114, 5283–5288. 10.1073/pnas.1619078114 PubMed DOI PMC

Spallek T., Gan P., Kadota Y., Shirasu K. (2018). Same tune, different song—cytokinins as virulence factors in plant–pathogen interactions? Curr. Opin. Plant Biol. 44, 82–87. 10.1016/j.pbi.2018.03.002 PubMed DOI

Stadnik M. J., Freitas M. B. D. (2014). Algal polysaccharides as source of plant resistance inducers. Trop. Plant Pathol. 39, 111–118. 10.1590/S1982-56762014000200001 DOI

Su Y., Xia S., Wang R., Xiao L. (2017). “Phytohormonal quantification based on biological principles,” in Hormone Metabolism and Signaling in Plants. Eds. Li J., Li C., Smith S. M. (London, UK: Academic Press; ), 431–470.

Uthirapandi V., Suriya S., Boomibalagan P., Eswaran S., Ramya S. S., Vijayanand N., et al. (2018). Bio-fertilizer potential of seaweed liquid extracts of marine macro algae on growth and biochemical parameters of Ocimum sanctum. J. Pharmacogn. Phytochem. 7, 3528–3532. archives/2018/vol7issue3/PartAV/7-3-244-742.pdf

Vrabka J., Niehaus E. M., Münsterkötter M., Proctor R. H., Brown D. W., Novák O., et al. (2018). Production and role of hormones during interaction of Fusarium species with maize (Zea mays L.) seedlings. Front. Plant Sci. 9, 1936. 10.3389/fpls.2018.01936 PubMed DOI PMC

Walters D. R., McRoberts N., Fitt B. D. (2008). Are green islands red herrings? Significance of green islands in plant interactions with pathogens and pests. Biol. Rev. 83, 79–102. 10.1111/j.1469-185X.2007.00033.x PubMed DOI

Wang C. J., Yang W., Wang C., Gu C., Niu D. D., Liu H. X., et al. (2012). Induction of drought tolerance in cucumber plants by a consortium of three plant growth-promoting rhizobacterium strains. PLoS ONE 7, e52565. 10.1371/journal.pone.0052565 PubMed DOI PMC

Weiss D., Ori N. (2007). Mechanisms of cross talk between gibberellin and other hormones. Plant Physiol. 144, 1240–1246. 10.1104/pp.107.100370 PubMed DOI PMC

Zhang H., Guiguet A., Dubreuil G., Kisiala A., Andreas P., Emery R. N., et al. (2017). Dynamics and origin of cytokinins involved in plant manipulation by a leaf-mining insect. Insect Sci. 24, 1065–1078. 10.1111/1744-7917.12500 PubMed DOI

Zhang H., Dubreuil G., Faivre N., Dobrev P., Kaiser W., Huguet E., et al. (2018). Modulation of plant cytokinin levels in the Wolbachia-free leaf-mining species. Phyllonorycter Mespilella. Entomolog. Exp. Appl. 16, 428–438. 10.1111/eea.12681 DOI

Zhou C., Zhu L., Xie Y., Li F. Y., Xiao X., Ma Z. Y., et al. (2017). Bacillus licheniformis SA03 confers increased saline-alkaline tolerance in chrysanthemum plants by induction of abscisic acid accumulation. Front. Plant Sci. 8, 1143. 10.3389/fpls.2017.01143 PubMed DOI PMC

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