In the complex process of homeostasis of phytohormones cytokinins (CKs), O-glucosylation catalyzed by specific O-glucosyltransferases represents one of important mechanisms of their reversible inactivation. The CK O-glucosyltransferases belong to a highly divergent and polyphyletic multigene superfamily of glycosyltransferases, of which subfamily 1 containing UDP-glycosyltransferases (UGTs) is the largest in the plant kingdom. It contains recently discovered O and P subfamilies present in higher plant species but not in Arabidopsis thaliana. The cis-zeatin O-glucosyltransferase (cisZOG) genes belong to the O subfamily encoding a stereo-specific O-glucosylation of cis-zeatin-type CKs. We studied different homologous genes, their domains and motifs, and performed a phylogenetic reconstruction to elucidate the plant evolution of the cisZOG gene. We found that the cisZOG homologs do not form a clear separate clade, indicating that diversification of the cisZOG gene took place after the diversification of the main angiosperm families, probably within genera or closely related groups. We confirmed that the gene(s) from group O is(are) not present in A. thaliana and is(are) also missing in the family Brassicaceae. However, cisZOG or its metabolites are found among Brassicaceae clade, indicating that remaining genes from other groups (UGT73-group D and UGT85-group G) are able, at least in part, to substitute the function of group O lost during evolution. This study is the first detailed evolutionary evaluation of relationships among different plant ZOGs within angiosperms.

Laboratory of Hormonal Regulations in Plants Institute of Experimental Botany of the Czech Academy of Sciences Rozvojová 263 165 02 Prague 6 Czech Republic

Laboratory of Pollen Biology Institute of Experimental Botany of the Czech Academy of Sciences Rozvojová 263 165 02 Prague 6 Czech Republic

Zobrazit více v PubMed

Spíchal L. Cytokinins—Recent news and views of evolutionally old molecules. Funct. Plant Biol. 2012;39:267–284. doi: 10.1071/FP11276. PubMed DOI

Hluska T, Hlusková L, Emery RJN. The Hulks and the Deadpools of the cytokinin universe: A dual strategy for cytokinin production, translocation, and signal transduction. Biomolecules. 2021;11:209. doi: 10.3390/biom11020209. PubMed DOI PMC

Pokorná E, Hluska T, Galuszka P, Hallmark HT, Dobrev PI, Záveská Drábková L, Filipi T, Holubová K, Plíhal O, Rashotte AM, Filepová R, Malbeck J, Novák O, Spíchal L, Brzobohatý B, Mazura P, Zahajská L, Motyka V. Cytokinin N-glucosides: Occurrence, metabolism and biological activities in plants. Biomolecules. 2021;11:24. doi: 10.3390/biom11010024. PubMed DOI PMC

Yonekura-Sakakibara K, Hanada K. An evolutionary view of functional diversity in family 1 glycosyltransferases. Plant J. 2011;66:182–193. doi: 10.1111/j.1365-313X.2011.04493.x. PubMed DOI

Li Y, Baldauf S, Lim E-K, Bowles DJ. Phylogenetic analysis of the UDP-glycosyltransferase multigene family of Arabidopsis thaliana. J. Biol. Chem. 2001;276:4338–4343. doi: 10.1074/jbc.M007447200. PubMed DOI

Mackenzie PI, Owens IS, Burchel B, Bock KW, Bairoch A, Bélanger A, et al. The UDP glucosyltransferase gene family: Recommended nomenclature updated based on evolutionary divergence. Pharmacogenetics. 1997;7:255–269. doi: 10.1097/00008571-199708000-00001. PubMed DOI

Bowles D, Isayenkova J, Lim EK, Poppenberger B. Glycosyltransferases: Managers of small molecules. Curr. Opin. Plant Biol. 2005;8:254–263. doi: 10.1016/j.pbi.2005.03.007. PubMed DOI

Ross J, Li Y, Lim E-K, Bowles DJ. Higher plant glycosyltransferases. Genome Biol. 2001;2:reviews3004. doi: 10.1186/gb-2001-2-2-reviews3004. PubMed DOI PMC

Caputi L, Malnoy M, Goremykin V, Nikiforova S, Materns S. A genome-wide phylogenetic reconstruction of family 1 UDP-glycosyltransferases revealed the expansion of the family during the adaptation of plants to life on land. Plant J. 2012;69:1030–1042. doi: 10.1111/j.1365-313X.2011.04853.x. PubMed DOI

Huang J, Pang C, Fan C, Song M, Yu J, Wei H, et al. Genome-wide analysis of the family 1 glycosyltransferases in cotton. Mol. Genet. Genom. 2015;290:1805–1818. doi: 10.1007/s00438-015-1040-8. PubMed DOI

Rohmer M. Mevalonate-independent methylerythritol phosphate pathway for isoprenoid biosynthesis. Elucidation and distribution. Pure Appl. Chem. 2003;75:375–387. doi: 10.1351/pac200375020375. DOI

Kasahara H, Takei K, Ueda N, Hishiyama S, Yamaya T, Kamiyam Y, et al. Distinct isoprenoid origins of cis and trans-zeatin biosyntheses in Arabidopsis. J. Biol. Chem. 2004;279:14049–14054. doi: 10.1074/jbc.M314195200. PubMed DOI

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

Åstot C, Doležal K, Nordström A, Wang Q, Kunkel T, Moritz T, et al. An alternative cytokinin biosynthesis pathway. PNAS. 2000;97:14778–14783. doi: 10.1073/pnas.260504097. PubMed DOI PMC

Kamínek M. Evolution of tRNA and origin of the two positional isomers of zeatin. J. Theor. Biol. 1974;48:489–492. doi: 10.1016/S0022-5193(74)80018-4. PubMed DOI

Persson BC, Esberg B, Ólafsson Ó, Björk GR. Synthesis and function of isopentenyl adenosine derivatives in tRNA. Biochimie. 1994;76:1152–1160. doi: 10.1016/0300-9084(94)90044-2. PubMed DOI

Gajdošová S, Spíchal L, Kamínek M, Hoyerová K, Novák O, Dobrev PI, Galuszka P, Klíma P, Gaudinová A, Žižková E, Hanuš J, Dančák M, Trávníček B, Pešek B, Krupička M, Vaňková R, Strnad M, Motyka V. Distribution, biological activities, metabolism, and the conceivable function of cis-zeatin-type cytokinins in plants. J. Exp. Bot. 2011;62:2827–2840. doi: 10.1093/jxb/erq457. PubMed DOI

Klämbt D. The biogenesis of cytokinins in higher plants: Our present knowledge. In Physiology and Biochemistry of Cytokinins in Plants. (eds. Kamínek, M., Mok, D. W. S. & Zažímalová, E.) 25–27 (SPB Academic, 1992).

Dixon SC, Martin RC, Mok MC, Shaw G, Mok DWS. Zeatin glycosylation enzymes in Phaseolus. Isolation of O-glucosyltransferase from P. lunatus and comparison to O-xylosyltransferase from P. vulgaris. Plant Physiol. 1989;90:1316–1321. doi: 10.1104/pp.90.4.1316. PubMed DOI PMC

Turner JE, Mok DWS, Mok MC, Shaw G. Isolation and partial purification of an enzyme catalyzing the formation of O-xylosylzeatin in Phaseolus vulgaris embryos. Proc. Natl. Acad. Sci. U. S. A. 1987;84:3714–3717. doi: 10.1073/pnas.84.11.3714. PubMed DOI PMC

Martin RC, Mok MC, Mok DWS. Isolation of a cytokinin gene, ZOG1, encoding zeatin O-glucosyltransferase from Phaseolus lunatus. Proc. Natl. Acad. Sci. U. S. A. 1999;96:284–289. doi: 10.1073/pnas.96.1.284. PubMed DOI PMC

Martin RC, Mok MC, Mok DW. A gene encoding the cytokinin enzyme zeatin O-xylosyltransferase of Phaseolus vulgaris. Plant Physiol. 1999;120:553–558. doi: 10.1104/pp.120.2.553. PubMed DOI PMC

Martin RC, Mok MC, Habben JE, Mok DW. A maize cytokinin gene encoding an O-glucosyltransferase specific to cis-zeatin. PNAS. 2001;98:5922–5926. doi: 10.1073/pnas.101128798. PubMed DOI PMC

Veach YK, Martin RC, Mok DWS, Malbeck J, Vaňková R, Mok MC. O-Glucosylation of cis-zeatin in maize characterization of genes, enzymes, and endogenous cytokinins. Plant Phys. 2003;131:1374–1380. doi: 10.1104/pp.017210. PubMed DOI PMC

Kudo T, Makita N, Kojima M, Tokunaga H, Sakakibara H. Cytokinin Activity of cis-zeatin and phenotypic alterations induced by overexpression of putative cis-zeatin-O-glucosyltransferase in rice. Plant Physiol. 2012;160:319–331. doi: 10.1104/pp.112.196733. PubMed DOI PMC

Hou B, Lim E-K, Higgins GS, Bowles DJ. N-glucosylation of cytokinins by glycosyltransferases of Arabidopsis thaliana. J. Biol. Chem. 2004;279:47822–47832. doi: 10.1074/jbc.M409569200. PubMed DOI

Poppenberger B, Fujioka S, Soeno K, George GL, Vaistij FE, Hiranuma S, Seto H, Takatsuto S, Adam G, Yoshida S, Bowles D. The UGT73C5 of Arabidopsis thaliana glucosylates brassinosteroids. Proc. Natl. Acad. Sci. U. S. A. 2005;102:15253–15258. doi: 10.1073/pnas.0504279102. PubMed DOI PMC

Gandia-Herrero F, Lorenz A, Larson T, Graham IA, Bowles DJ, Rylott EL, Bruce NC. Detoxification of the explosive 2,4,6-trinitrotoluene in Arabidopsis: Discovery of bifunctional O- and C-glucosyltransferases. Plant J. 2008;56:963–974. doi: 10.1111/j.1365-313X.2008.03653.x. PubMed DOI

Jin S-H, Ma X-M, Kojima M, Sakakibara H, Wang Y-W, Hou B-K. Overexpression of glucosyltransferase UGT85A1 influences trans-zeatin homeostasis and trans-zeatin responses likely through O-glucosylation. Planta. 2013;237:991–999. doi: 10.1007/s00425-012-1818-4. PubMed DOI

Šmehilová M, Dobrůšková J, Novák O, Takáč T, Galuszka P. Cytokinin-specific glycosyltransferases possess different roles in cytokinin homeostasis maintenance. Front. Plant Sci. 2016;7:1264. doi: 10.3389/fpls.2016.01264. PubMed DOI PMC

Swigoňová Z, Bennetzen JL, Messig J. Structure and evolution of the r/b chromosomal regions in rice, maize and sorgum. Genetics. 2005;169:891–906. doi: 10.1534/genetics.104.034629. PubMed DOI PMC

Paquette S, Lindberg Møller B, Bak S. On the origin of family 1 plant glycosyltransferases. Phytochemistry. 2003;62:399–413. doi: 10.1016/S0031-9422(02)00558-7. PubMed DOI

Osmani SA, Bak S, Imberty A, Olsen CE, Møller BL. Catalytic key amino acids and UDP-sugar donor specificity of a plant glucuronosyltransferase UGT94B1: Molecular modeling substantiated by site-specific mutagenesis and biochemical analyses. Plant Physiol. 2008;48:1295–1308. doi: 10.1104/pp.108.128256. PubMed DOI PMC

Kubo A, Arai Y, Nagashima S, Yoshikawa T. Alteration of sugar donor specificities of plant glycosyltransferases by a single point mutation. Arch. Biochem. Biophys. 2004;429:198–203. doi: 10.1016/j.abb.2004.06.021. PubMed DOI

Ono E, Homma Y, Horikawa M, Kunikane-Doi S, Imai H, Takahashi S, Kawai Y, Ishiguro M, Fukui Y, Nakayama T. Functional differentiation of the glycosyltransferases that contribute to the chemical diversity of bioactive flavonol glycosides in grapevines (Vitis vinifera) Plant Cell. 2010;22:2856–2871. doi: 10.1105/tpc.110.074625. PubMed DOI PMC

Schweiger W, Pasquet J-C, Nussbaumer T, Kovalsky Paris MP, Wiesenberger GW, et al. Functional characterization of two clusters of Brachypodium distachyon UDP-glycosyltransferases encoding putative deoxynivalenol detoxification genes. MPMI. 2013;26:781–792. doi: 10.1094/MPMI-08-12-0205-R. PubMed DOI

Spíchal L. Cytokinins—Recent news of old molecules. Funct. Plant Biol. 2012;39:267–284. doi: 10.1071/FP11276. PubMed DOI

Rubinstein CV, Gerriene P, de la Puente GS, Astini RA, Steemans P. Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana) New Phytol. 2010;188:365–369. doi: 10.1111/j.1469-8137.2010.03433.x. PubMed DOI

Záveská Drábková L, Honys D. Evolutionary history of callose synthases in terrestrial plants with emphasis on proteins involved in male gametophyte development. PLoS ONE. 2017;13:e0187331. doi: 10.1371/journal.pone.0187331. PubMed DOI PMC

Little A, Schwerdt JG, Shirley NJ, Khor SF, Neumann K, O´Donovan LA, et al. Revised phylogeny of cellulose synthase gene superfamily: Insights into cell wall evolution. Plant. Phys. 2018;117:1124–1141. doi: 10.1104/pp.17.01718. PubMed DOI PMC

Landis JB, Soltis DE, Li Z, Marx HE, Barker MS, Tank DC, Soltis PS. Impact of whole-genome duplication events on diversification rates in angiosperms. Am. J. Bot. 2018;105:348–363. doi: 10.1002/ajb2.1060. PubMed DOI

Freeling M. Bias in plant gene content following different sorts of duplication: Tandem, whole-genome, segmental, or by transposition. Ann. Rev. Plant. Biol. 2009;60:433–453. doi: 10.1146/annurev.arplant.043008.092122. PubMed DOI

Choi IG, Kim SH. Evolution of protein structural classes and protein sequence families. PNAS. 2006;3:14056–14061. doi: 10.1073/pnas.0606239103. PubMed DOI PMC

Sikosek, T. & Bornberg-Bauer, E. Evolution before and after gene duplication? In Evolution After Gene Duplication (eds. Dittmar, K. & Liberles, D.) 106–131 (Wiley-Blackwell, 2010).

Tiley GP, Ané C, Burleigh G. Evaluating and characterizing ancient whole-genome duplications in plants with gene count data. Genome Biol. Evol. 2015;8(4):1023–1037. doi: 10.1093/gbe/evw058. PubMed DOI PMC

de Bruijn S, Zhao T, Muiño JM, Schranz EM, Angenent GC, Kaufmann K. PISTILLATA paralogs in Tarenaya hassleriana have diverged in interaction specificity. BMC Plant Biol. 2018;18:368. doi: 10.1186/s12870-018-1574-0. PubMed DOI PMC

Mei W, Boatwright L, Feng G, Schnable JC, Barbazuk WB. Evolutionarily conserved alternative splicing across monocots. Genetics. 2017;207:465–480. doi: 10.1534/genetics.117.300189. PubMed DOI PMC

Marquez Y, Brown JWS, Simpson C, Barta A, Kalyna M. Transcriptome survey reveals increased complexity of the alternative splicing landscape in Arabidopsis. Genome Res. 2012;22:1184–1195. doi: 10.1101/gr.134106.111. PubMed DOI PMC

Reddy ASN, Marquez Y, Kalyna M, Barta A. Complexity of the alternative splicing landscape in plants. Plant Cell. 2013;25:3657–3683. doi: 10.1105/tpc.113.117523. PubMed DOI PMC

Shang X, Cao Y, Ma L. Alternative splicing in plant genes: A means of regulating the environmental fitness of plants. Int. J. Mol. Sci. 2017;18:432. doi: 10.3390/ijms18020432. PubMed DOI PMC

Hughes J, Hughes MA. Multiple secondary plant product UDP-glucose glucosyltransferase genes expressed in cassava. DNA Seq. 1994;5:41–49. doi: 10.3109/10425179409039703. PubMed DOI

Ostrowski M, Jakubovska A. UDP-glycosyltransferases of plant hormones. Adv. Cell Biol. 2014;4:43–60. doi: 10.2478/acb-2014-0003. DOI

Baker MS, Vogel H, Schranz ME. Paleopolyploidy in the Brassicales: Analyses of the cleome transcriptome elucidate the history of genome duplications in Arabidopsis and other Brassicales. Genome Biol. Evol. 2009;1:391–399. doi: 10.1093/gbe/evp040. PubMed DOI PMC

Lyons E, Pedersen B, Kane J, Alam M, Ming R, Tang H, et al. Finding and comparing syntenic regions among Arabidopsis and the outgroups papaya, poplar, and grape: CoGe with rosids. Plant Physiol. 2008;148:1772–1781. doi: 10.1104/pp.108.124867. PubMed DOI PMC

Schranz ME, Mitchell-Olds T. Independent ancient polyploidy events in the sister families Brassicaceae and Cleomaceae. Plant Cell. 2006;18:1152–1165. doi: 10.1105/tpc.106.041111. PubMed DOI PMC

Ming R, Hou S, Feng Y, Yu Q, Dionne-Laporte A, Saw JH, et al. The draft genome of the transgenic tropical fruit tree papaya (Carica papaya L.) Nature. 2008;452:991–996. doi: 10.1038/nature06856. PubMed DOI PMC

The Brassica rapa Genome Sequencing Consortium The genome of the mesopolyploid crop species Brassica rapa. Nat. Genet. 2011;43:1035–1039. doi: 10.1038/ng.919. PubMed DOI

Dassanayake M, Oh D-H, Haas JS, Hernandez A, Hong H, Ali S, et al. The genome of the extremophile crucifer Thellungiella parvula. Nat. Genet. 2011;43:913–918. doi: 10.1038/ng.889. PubMed DOI PMC

Rockinger A, Souza A, Carvalho FA, Renner SS. Chromosome number reduction in the sister clade of Carica papaya with concomitant genome size doubling. Am. J. Bot. 2016;103:1082–1088. doi: 10.3732/ajb.1600134. PubMed DOI

Tang H, Bowers JE, Wang X, Ming R, Alam M, Paterson AH. Synteny and collinearity in plant genomes. Science. 2008;320:486–488. doi: 10.1126/science.1153917. PubMed DOI

Rice A, Glick L, Abadi S, Einhorn M, Kopelman NM, Salman-Minkov A, et al. The chromosome counts database (CCDB) A community resource of plant chromosome numbers. New Phytol. 2015;206:19–26. doi: 10.1111/nph.13191. PubMed DOI

Gschwend AR, Wai CM, Zee F, Arumuganathan AK, Ming R. Genome size variation among sex types in dioecious and trioecious Caricaceae species. Euphytica. 2013;189:461–469. doi: 10.1007/s10681-012-0815-9. DOI

Tang HB, Wang XY, Bowers JE, Ming R, Alam M, Paterson AH, et al. Unraveling ancient hexaploidy through multiply-aligned angiosperm gene maps. Genome Res. 2008;18:1944–1954. doi: 10.1101/gr.080978.108. PubMed DOI PMC

Tsitsekian D, Daras G, Alatzas A, Templalexis D, Hatzopoulos P, Rigas S. Comprehensive analysis of Lon proteases in plants highlights independent gene duplication events. J. Exp. Bot. 2019;70:2185–2197. doi: 10.1093/jxb/ery440. PubMed DOI PMC

Edger PP, Heidel-Fischer HM, Bekaert M, Rota J, Glöckner G, Platts AE, et al. The butterfly plant arms-race escalated by gene and genome duplications. PNAS. 2015;112:8362–8366. doi: 10.1073/pnas.1503926112. PubMed DOI PMC

Salse J. Ancestors of modern plant crops. Curr. Opin. Plant. Biol. 2016;30:134–142. doi: 10.1016/j.pbi.2016.02.005. PubMed DOI

Barvkar VT, Pardeshi VC, Kale SM, Kadoo NY, Gupta VS. Phylogenomic analysis of UDP glycosyltransferase 1 multigene family in Linum usitatissimum identified genes with varied expression patterns. BMC Genom. 2012;13:175. doi: 10.1186/1471-2164-13-175. PubMed DOI PMC

Horgan R. A new cytokinin metabolite. Biochem. Biophys. Res. Commun. 1975;65:358–363. doi: 10.1016/S0006-291X(75)80101-X. PubMed DOI

Parker CW, Letham DS, Wilson MM, Jenkins ID, MacLeod JK, Summons RE. The identity of two new cytokinin metabolites. Ann. Bot. 1975;39:375–376. doi: 10.1093/oxfordjournals.aob.a084951. DOI

Takagi M, Yokota T, Murofushi N, Saka H, Takahashi N. Quantitative changes of free-base, riboside, ribotide and glucoside cytokinins in developing rice grains. Plant Growth Regul. 1989;8:349–364. doi: 10.1007/BF00024665. DOI

Wagner BM, Beck E. Cytokinins in the perennial herb Urtica dioica L. as influenced by its nitrogen status. Planta. 1993;190:511–518. doi: 10.1007/BF00224790. DOI

Schäfer M, Brütting C, Canales IM, Großkinsky DK, Vaňková R, Baldwin IT, Meldau S. The role of cis-zeatin-type cytokinins in plant growth regulation and mediating responses to environmental interactions. J. Exp. Bot. 2015;66:4873–4884. doi: 10.1093/jxb/erv214. PubMed DOI PMC

Goodstein DM, Shu S, Howson R, Neupane R, Hayes RD, Fazo J, et al. Phytozome: A comparative platform for green plant genomics. Nucleic Acids Res. 2012;40:1178–1186. doi: 10.1093/nar/gkr944. PubMed DOI PMC

Chen Y, Zou M, Cao Y. Transcriptome analysis of the Arabidopsis semi-in vivo pollen tube guidance system uncovers a distinct gene expression profile. J. Plant. Biol. 2014;57:93–105. doi: 10.1007/s12374-013-0272-6. DOI

Philippon H, Souvane A, Brochier-Armanet C, Perrière G. IsoSel: Protein Isoform Selector for phylogenetic reconstructions. PLoS ONE. 2017;12:e0174250. doi: 10.1371/journal.pone.0174250. PubMed DOI PMC

Sievers F, Wilm A, Dineen D, Gibson TJ, Karplus K, Li W, et al. Fast, scalable generation of high-quality protein multiple sequence alignments using Clustal Omega. Mol. Syst. Biol. 2011;7:539. doi: 10.1038/msb.2011.75. PubMed DOI PMC

Néron B, Ménager H, Maufrais C, Joly N, Maupetit J, Letort S, et al. Mobyle: A new full web bioinformatics framework. Bioinformatics. 2009;25:3005–3011. doi: 10.1093/bioinformatics/btp493. PubMed DOI PMC

Söding J. Protein homology detection by HMM–HMM comparison. Bioinformatics. 2005;21:951–960. doi: 10.1093/bioinformatics/bti125. PubMed DOI

Hall TA. BioEdit: A user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl. Acids Symp. 1999;41:95–98.

Bailey TL, Bodén M, Buske FA, Frith M, Grant CE, Clementi L, et al. MEME SUITE: Tools for motif discovery and searching. Nucl. Acids Res. 2009;37:W202–W208. doi: 10.1093/nar/gkp335. PubMed DOI PMC

Bateman A, Birney E, Cerruti L, Durbin R, Etwiller L, Eddy SR, et al. The Pfam protein families database. Nucl. Acids Res. 2002;30(1):276–280. doi: 10.1093/nar/30.1.276. PubMed DOI PMC

Geer LY, Domarchev M, Lipman DJ, Bryant SH. CDART: Protein homology by domain architecture. Genome Res. 2002;12(10):1619–1623. doi: 10.1101/gr.278202. PubMed DOI PMC

Hu B, Jin J, Guo A-Y, Zhang H, Luo J, Gao G. GSDS 2.0: An upgraded gene feature visualization server. Bioinformatics. 2015;31:1296–1297. doi: 10.1093/bioinformatics/btu817. PubMed DOI PMC

Stamatakis A. RAxML version 8: A tool for phylogenetic analysis and post-analysis of large phylogenies. Bioinformatics. 2014;30:1312–1313. doi: 10.1093/bioinformatics/btu033. PubMed DOI PMC

Nei M, Kumar S. Molecular Evolution and Phylogenetics. Oxford University Press; 2000.

Kumar S, Stecher G, Tamura K. MEGA7: Molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol. Biol. Evol. 2016;33:1870–1874. doi: 10.1093/molbev/msw054. PubMed DOI PMC

Felsenstein J. Confidence limits on phylogenies: An approach using the bootstrap. Evolution. 1985;39:783–791. doi: 10.1111/j.1558-5646.1985.tb00420.x. PubMed DOI

Letunic I, Bork P. Interactive Tree Of Life (iTOL) v3: An online tool for the display and annotation of phylogenetic and other trees. Nucleic Acids Res. 2016;8:W242–W245. doi: 10.1093/nar/gkw290. PubMed DOI PMC

Desiccation as a Post-maturation Treatment Helps Complete Maturation of Norway Spruce Somatic Embryos: Carbohydrates, Phytohormones and Proteomic Status