Exogenous GA3 promotes flowering in Paphiopedilum callosum (Orchidaceae) through bolting and lateral flower development regulation

Abstract

Paphiopedilum orchids have a high ornamental value, and their flower abundance and timing are both key horticultural traits regulated by phytohormones. All one-flowered Paphiopedilum have additional lateral buds in the apical bract that fail to develop. In this study, an exogenous gibberellin (GA₃) application promoted flowering of Pathiopedilum callosum by inducing its early bolting instead of the floral transition of dominant flowers. Applying GA₃ effectively promoted lateral flower differentiation, resulting in a two-flowered inflorescence. GA-promoted lateral flower formation involved GA interacting with indole-3-acetic acid (IAA) and cytokinins (CTKs), given the decreased CTK content and downregulated expression of CTK synthesis genes, the increased IAA content and downregulated expression of IAA degradation, and the upregulated expression of transport genes. Further, GA acted via PcDELLA, PcTCP15, and PcXTH9 expressed in stage 5 to promote bolting, and via expression of PcAP3, PcPI, and PcSEP to promote flowering. This study provides insight into mechanisms regulating flower development of P. callosum.

References

[1] Cribb P . Morphology. In: Mathew B, ed. The Genus Paphiopedilum 2nd ed. Natural History Publications (Borneo) and The Royal Botanic Gardens: Kew, 1987, 4-5.

[2] Rotor G, Withner C. The photoperiodic and temperature responses of orchids. In: Withner C, ed. The Orchids.New York: Ronald Press: New York, 1959, 397-416.

[3] Cribb P. Taxonomy. In: Mathew B, ed. The Genus Paphiopedilum 2nd ed. Natural History Publications (Borneo) and The Royal Botanic Gardens: Kew, 1987, 331-6.

[4] Bao S, Hua C, Shen L et al. New insights into gibberellin signaling in regulating flowering in Arabidopsis . J Integr Plant Biol. 2020; 62: 118-31.

[5] Yamaguchi S . Gibberellin metabolism and its regulation. Annu Rev Plant Biol. 2008; 59: 225-51.

[6] Murase K, Hirano Y, Sun TP et al. Gibberellin-induced DELLA recognition by the gibberellin receptor GID1. Nature. 2008; 456: 459-63.

[7] Ueguchi-Tanaka M, Ashikari M, Nakajima M et al. GIBBERELLIN INSENSITIVE DWARF1 encodes a soluble receptor for gibberellin. Nature. 2005; 437: 693-8.

[8] Daviere JM, Achard P . A pivotal role of DELLAs in regulating multiple hormone signals. Mol Plant. 2016; 9: 10-20.

[9] Hedden P, Phillips AL . Gibberellin metabolism: new insights revealed by the genes. Trends Plant Sci. 2000; 5: 523-30.

[10] Sun TP . Gibberellin metabolism, perception and signaling pathways in Arabidopsis . In: Arabidopsis Book.Vol. 6. 2008, e0103.

[11] Cucinotta M, Cavalleri A, Chandler JW et al. Auxin and flower development: a blossoming field. Cold Spring Harb Perspect Biol. 2021; 13.

[12] Izawa T. What is going on with the hormonal control of flowering in plants? Plant J . 2021; 105: 431-45.

[13] Martignago D, Siemiatkowska B, Lombardi A et al. Abscisic acid and flowering regulation: many targets, different places. Int J Mol Sci. 2020; 21: 9700.

[14] Mashiguchi K, Tanaka K, Sakai T et al. The main auxin biosynthesis pathway in Arabidopsis . Proc Natl Acad Sci USA. 2011; 108: 18512-7.

[15] Won C, Shen X, Mashiguchi K et al. Conversion of tryptophan to indole-3-acetic acid by TRYPTOPHAN AMINOTRANSFERASES OF ARABIDOPSIS and YUCCAs in Arabidopsis . Proc Natl Acad Sci USA. 2011; 108: 18518-23.

[16] Zhang J, Peer WA . Auxin homeostasis: the DAO of catabolism. J Exp Bot. 2017; 68: 3145-54.

[17] Adamowski M, Friml J . PIN-dependent auxin transport: action, regulation, and evolution. Plant Cell. 2015; 27: 20-32.

[18] Leyser O. Auxin signaling. Plant Physiol. 2018; 176: 465-79.

[19] Kieber JJ, Schaller GED . Cytokinin signaling in plant development. Development. 2018; 145: dev149344.

[20] Davière J-M, Wild M, Regnault T et al. Class I TCP-DELLA interactions in inflorescence shoot apex determine plant height. Curr Biol. 2014; 24: 1923-8.

[21] Martín-Trillo M, Cubas P . TCP genes: a family snapshot ten years later. Trends Plant Sci. 2010; 15: 31-9.

[22] Hyodo H, Yamakawa S, Takeda Y et al. Active gene expression of a xyloglucan endotransglucosylase/hydrolase gene, XTH9, in inflorescence apices is related to cell elongation in Arabidopsis thaliana . Plant Mol Biol. 2003; 52: 473-82.

[23] van der Knaap E, Kim JH, Kende H . A novel gibberellin-induced gene from rice and its potential regulatory role in stem growth. Plant Physiol. 2000; 122: 695-704.

[24] Uchida N, Suk Lee J, Horst RJ et al. Regulation of inflorescence architecture by intertissue layer ligand-receptor communication between endodermis and phloem. Proc Natl Acad Sci USA. 2012; 109: 6337-42.

[25] Lee HB, Im NH, An SK et al. Changes of growth and inflorescence initiation by exogenous gibberellic acid₃ and 6-benzylaminopurine application in Phalaenopsis orchids. Agronomy. 2021; 11: 196.

[26] Sumitomo K, Li T, Hisamatsu T . Gibberellin promotes flowering of chrysanthemum by upregulating CmFL, a chrysanthemum FLORICAULA/LEAFY homologous gene. Plant Sci. 2009; 176: 643-9.

[27] Li W, Yong Y, Zhang Y et al. Transcriptional regulatory network of GA floral induction pathway in LA hybrid lily. Int J Mol Sci. 2019; 20.

[28] Fan S, Zhang D, Gao C et al. Mediation of flower induction by gibberellin and its inhibitor paclobutrazol: mRNA and miRNA integration comprises complex regulatory cross-talk in apple. Plant Cell Physiol. 2018; 59: 2288-307.

[29] Goldberg-Moeller R, Shalom L, Shlizerman L et al. Effects of gibberellin treatment during flowering induction period on global gene expression and the transcription of flowering-control genes in citrus buds. Plant Sci. 2013; 198: 46-57.

[30] Chen W-S, Chang H-W, Chen W-H et al. Gibberellic acid and cytokinin affect Phalaenopsis flower morphology at high temperature. HortScience. 1997; 32: 1069-73.

[31] Su W-R, Chen WS, Koshioka M et al. Changes in gibberellin levels in the flowering shoot of Phalaenopsis hybrida under high temperature conditions when flower development is blocked. Plant Physiol Biochem. 2001; 39: 45-50.

[32] Goh C . Hormonal regulation of flowering in a sympodial orchid hybrid Dendrobium Louisae. New Phytol. 1979; 82: 375-80.

[33] Cardoso JC, Ono EO, Rodrigues JD . Gibberellic acid and water regime in the flowering induction of Brassocattleya and Cattleya hybrid orchids . Hortic Bras. 2010; 28: 395-8.

[34] Matsumoto TK . Gibberellic acid and benzyladenine promote early flowering and vegetative growth of Miltoniopsis orchid hybrids. HortScience. 2006; 41: 131-5.

[35] Dahlia K. Paphiopedilum flowering induction with light intensity and growth regulator substance . AIP Conference Proceedings. 2016; 1744: 020010.

[36] Miguel T, Sakai W, Fang J . Gibberellic acid induced flowering of Paphiopedilum (Macabre × glanduliferum) . In: XXVII International Horticultural Congress - IHC2006. International Symposium on Ornamentals, Now! Acta Hortic. 2006; 766: 279-82.

[37] Wilson RN, Heckman JW, Somerville CR . Gibberellin is required for flowering in Arabidopsis thaliana under short days. Plant Physiol. 1992; 100: 403-8.

[38] Okamuro JK, den Boer BG, Lotys-Prass C et al. Flowers into shoots: photo and hormonal control of a meristem identity switch in Arabidopsis . Proc Natl Acad Sci USA. 1996; 93: 13831-6.

[39] Okamuro JK, Szeto W, Lotys-Prass C et al. Photo and hormonal control of meristem identity in the Arabidopsis flower mutants apetala2 and apetala1 . Plant Cell. 1997; 9: 37-47.

[40] Yanai O, Shani E, Dolezal K et al. Arabidopsis KNOXI proteins activate cytokinin biosynthesis . Curr Biol. 2005; 15: 1566-71.

[41] Reinhardt D, Mandel T, Kuhlemeier C . Auxin regulates the initiation and radial position of plant lateral organs. Plant Cell. 2000; 12: 507-18.

[42] Fukazawa J, Ohashi Y, Takahashi R et al. DELLA degradation by gibberellin promotes flowering via GAF1-TPR-dependent repression of floral repressors in Arabidopsis . Plant Cell. 2021; 33: 2258-72.

[43] Yu H, Ito T, Zhao Y et al. Floral homeotic genes are targets of gibberellin signaling in flower development. Proc Natl Acad Sci USA. 2004; 101: 7827-32.

[44] Hamano M, Yamato Y, Yamazaki H et al. Endogenous gibberellins and their effects on flowering and stem elongation in cabbage (Brassica oleracea var. capitata) . J Hortic Sci. 2002; 77: 220-5.

[45] Zeevaart JA . Effects of photoperiod on growth rate and endogenous gibberellins in the long-day rosette plant spinach. Plant Physiol. 1971; 47: 821-7.

[46] GB JR . Daylength and temperature in relation to growth and flowering of orchids. Cornell Univ Agric Exp Stn Bull. 1952; 885: 1-47.

[47] Sachs RM . Stem elongation. Annu Rev Plant Biol. 1965; 16: 73-96.

[48] McKim SM . Moving on up-controlling internode growth. New Phytol. 2020; 226: 672-8.

[49] Sachs R, Bretz C, Lang A . Cell division and gibberellic acid. Exp Cell Res. 1959; 18: 230-44.

[50] Fang L, Kong X, Wen Y et al. Characterization of embryo and protocorm development of Paphiopedilum spicerianum . Plant Physiol Biochem. 2021; 167: 1024-34.

[51] Grabherr MG, Haas BJ, Yassour M et al. Full-length transcriptome assembly from RNA-Seq data without a reference genome. Nat Biotechnol. 2011; 29: 644-52.

[52] Livak KJ, Schmittgen TD . Analysis of relative gene expression data using real-time quantitative PCR and the 2^-ΔΔ(T) method . Methods. 2001; 25: 402-8.