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Iiyama CM, Vilcherrez-Atoche JA, Germanà MA, Vendrame WA, Cardoso JC. Breeding of ornamental orchids with focus on Phalaenopsis: current approaches, tools, and challenges for this century. Heredity (Edinb) 2024; 132:163-178. [PMID: 38302667 PMCID: PMC10997592 DOI: 10.1038/s41437-024-00671-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 01/09/2024] [Accepted: 01/11/2024] [Indexed: 02/03/2024] Open
Abstract
Ornamental orchid breeding programs have been conducted to develop commercially valuable cultivars with improved characteristics of commercial interest, such as size, flower color, pattern, shape, and resistance to pathogens. Conventional breeding, including sexual hybridization followed by selection of desirable characteristics in plants, has so far been the main method for ornamental breeding, but other techniques, including mutation induction by polyploidization and gamma irradiation, and biotechnological techniques, such as genetic transformation, have also been studied and used in ornamental breeding programs. Orchids are one of the most commercially important families in floriculture industry, having very particular reproductive biology characteristics and being a well-studied group of ornamentals in terms of genetic improvement. The present review focuses on the conventional and biotechnological techniques and approaches specially employed in breeding Phalaenopsis orchids, the genus with highest worldwide importance as an ornamental orchid, highlighting the main limitations and strengths of the approaches. Furthermore, new opportunities and future prospects for ornamental breeding in the CRISPR/Cas9 genome editing era are also discussed. We conclude that conventional hybridization remains the most used method to obtain new cultivars in orchids. However, the emergence of the first biotechnology-derived cultivars, as well as the new biotechnological tools available, such as CRISPR-Cas9, rekindled the full potential of biotechnology approaches and their importance for improve ornamental orchid breeding programs.
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Affiliation(s)
- Carla Midori Iiyama
- Laboratory of Plant Physiology and Tissue Culture, Department of Biotechnology, Plant and Animal Production, Centro de Ciências Agrárias, Universidade Federal de São Carlos (CCA/UFSCar), Rodovia Anhanguera, km 174, CEP13600-970, Araras, SP, Brazil.
- Graduate Program in Plant Production and Associated Bioprocesses, CCA/UFSCar, Araras, Brazil.
| | - Joe Abdul Vilcherrez-Atoche
- Laboratory of Plant Physiology and Tissue Culture, Department of Biotechnology, Plant and Animal Production, Centro de Ciências Agrárias, Universidade Federal de São Carlos (CCA/UFSCar), Rodovia Anhanguera, km 174, CEP13600-970, Araras, SP, Brazil
- Graduate Program in Plant Production and Associated Bioprocesses, CCA/UFSCar, Araras, Brazil
| | - Maria Antonietta Germanà
- Dipartimento Scienze Agrarie, Alimentari e Forestali (SAAF), Università degli Studi di Palermo, Palermo, Italy
| | - Wagner Aparecido Vendrame
- Environmental Horticulture Department, University of Florida, 2550 Hull Rd., Gainesville, FL, 32611, USA
| | - Jean Carlos Cardoso
- Laboratory of Plant Physiology and Tissue Culture, Department of Biotechnology, Plant and Animal Production, Centro de Ciências Agrárias, Universidade Federal de São Carlos (CCA/UFSCar), Rodovia Anhanguera, km 174, CEP13600-970, Araras, SP, Brazil.
- Graduate Program in Plant Production and Associated Bioprocesses, CCA/UFSCar, Araras, Brazil.
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Mehbub H, Akter A, Akter MA, Mandal MSH, Hoque MA, Tuleja M, Mehraj H. Tissue Culture in Ornamentals: Cultivation Factors, Propagation Techniques, and Its Application. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11233208. [PMID: 36501247 PMCID: PMC9736077 DOI: 10.3390/plants11233208] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/17/2022] [Accepted: 11/17/2022] [Indexed: 05/13/2023]
Abstract
Ornamentals come in a variety of shapes, sizes, and colors to suit a wide range of climates, landscapes, and gardening needs. Compared to demand, a shortage of plant materials and diversity force the search for solutions for their constant acquisition and improvement to increase their commercial value, respectively. In vitro cultures are a suitable solution to meet expectations using callus culture, somatic embryogenesis, protoplast culture, and the organogenesis of protocorm-like bodies; many of these techniques are commercially practiced. Factors such as culture media, explants, carbohydrates, plant growth regulators, and light are associated with the success of in vitro propagation. Techniques, especially embryo rescue and somatic hybridization, are widely used to improve ornamentals. The development of synthetic seed allows season-independent seed production and preservation in the long term. Despite the advantages of propagation and the improvement of ornamentals, many barriers still need to be resolved. In contrast to propagation and crop developmental studies, there is also a high scope for molecular studies, especially epigenetic changes caused by plant tissue culture of ornamentals. In this review, we have accumulated and discussed an overall update on cultivation factors, propagation techniques in ornamental plant tissue culture, in vitro plant improvement techniques, and future perspectives.
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Affiliation(s)
- Hasan Mehbub
- The United Graduate School of Agricultural Science, Ehime University, Matsuyama 790-8556, Japan
| | - Ayasha Akter
- Department of Horticulture, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Mst. Arjina Akter
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
- Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | | | - Md. Ashraful Hoque
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Monika Tuleja
- Department of Plant Cytology and Embryology, Institute of Botany, Faculty of Biology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland
| | - Hasan Mehraj
- Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan
- Correspondence: or
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Xia K, Zhang D, Xu X, Liu G, Yang Y, Chen Z, Wang X, Zhang GQ, Sun HX, Gu Y. Protoplast technology enables the identification of efficient multiplex genome editing tools in Phalaenopsis. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 322:111368. [PMID: 35780949 DOI: 10.1016/j.plantsci.2022.111368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Phalaenopsis orchids are popular ornamental plants worldwide. The application and optimization of efficient CRISPR-Cas genome editing toolkits in Phalaenopsis greatly accelerate the development of orchid gene function and breeding research. However, these methods are greatly hindered by the deficiency of a rapid screening system. In this study, we established a fast and convenient Phalaenopsis protoplast technology for the identification of functional genome editing tools. Two multiplex genome editing tools, PTG-Cas9-HPG (PTG, polycistronic tRNA-gRNA) system and RMC-Cpf1-HPG (RMC, ribozyme-based multi-crRNA) system, were developed for Phalaenopsis genome editing and further evaluated by established protoplast technology. We successfully detected various editing events comprising substitution and indel at designed target sites of the PDS gene and MADS gene, showing that both PTG-Cas9-HPG and RMC-Cpf1-HPG multiplex genome editing systems are functional in Phalaenopsis. Additionally, by optimizing the promoter that drives Cpf1 expression, we found that Super promoter can significantly improve the editing efficiency of the RMC-Cpf1-HPG system. Altogether, we successfully developed two efficient multiplex genome editing systems, PTG-Cas9-HPG and RMC-Cpf1-HPG, for Phalaenopsis, and the established protoplast-based screening technology provides a valuable foundation for developing more diverse and efficient genome editing toolkits and facilitating the development of orchid precision breeding.
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Affiliation(s)
- Keke Xia
- BGI-Shenzhen, Shenzhen 518083, China.
| | | | - Xiaojing Xu
- BGI-Shenzhen, Shenzhen 518083, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | | | - Yong Yang
- BGI-Shenzhen, Shenzhen 518083, China
| | | | | | - Guo-Qiang Zhang
- Laboratory for Orchid Conservation and Utilization, The Orchid Conservation and Research Center of Shenzhen, The National Orchid Conservation Center of China, Shenzhen 518114, China
| | - Hai-Xi Sun
- BGI-Shenzhen, Shenzhen 518083, China; BGI-Beijing, Beijing 100101, China.
| | - Ying Gu
- BGI-Shenzhen, Shenzhen 518083, China; Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen 518120, China.
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Ren R, Gao J, Yin D, Li K, Lu C, Ahmad S, Wei Y, Jin J, Zhu G, Yang F. Highly Efficient Leaf Base Protoplast Isolation and Transient Expression Systems for Orchids and Other Important Monocot Crops. FRONTIERS IN PLANT SCIENCE 2021; 12:626015. [PMID: 33659015 PMCID: PMC7917215 DOI: 10.3389/fpls.2021.626015] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/25/2021] [Indexed: 05/21/2023]
Abstract
Versatile protoplast platforms greatly facilitate the development of modern botany. However, efficient protoplast-based systems are still challenging for numerous horticultural plants and crops. Orchids are globally cultivated ornamental and medicinal monocot plants, but few efficient protoplast isolation and transient expression systems have been developed. In this study, we established a highly efficient orchid protoplast isolation protocol by selecting suitable source materials and optimizing the enzymatic conditions, which required optimal D-mannitol concentrations (0.4-0.6 M) combined with optimal 1.2% cellulose and 0.6% macerozyme, 5 μM of 2-mercaptoethanol and 6 h digestion. Tissue- and organ-specific protoplasts were successfully isolated from young leaves [∼3.22 × 106/g fresh weight (FW)], flower pedicels (∼5.26 × 106/g FW), and young root tips (∼7.66 × 105/g FW) of Cymbidium orchids. This protocol recommends the leaf base tissues (the tender part of young leaves attached to the stem) as better source materials. High yielding viable protoplasts were isolated from the leaf base of Cymbidium (∼2.50 × 107/g FW), Phalaenopsis (1.83 × 107/g FW), Paphiopedilum (1.10 × 107/g FW), Dendrobium (8.21 × 106/g FW), Arundina (3.78 × 106/g FW) orchids, and other economically important monocot crops including maize (Zea mays) (3.25 × 107/g FW) and rice (Oryza sativa) (4.31 × 107/g FW), which showed marked advantages over previous mesophyll protoplast isolation protocols. Leaf base protoplasts of Cymbidium orchids were used for polyethylene glycol (PEG)-mediated transfection, and a transfection efficiency of more than 80% was achieved. This leaf base protoplast system was applied successfully to analyze the CsDELLA-mediated gibberellin signaling in Cymbidium orchids. We investigated the subcellular localization of the CsDELLA-green fluorescent protein fusion and analyzed the role of CsDELLA in the regulation of gibberellin to flowering-related genes via efficient transient overexpression and gene silencing of CsDELLA in Cymbidium protoplasts. This protoplast isolation and transient expression system is the most efficient based on the documented results to date. It can be widely used for cellular and molecular studies in orchids and other economically important monocot crops, especially for those lacking an efficient genetic transformation system in vivo.
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Affiliation(s)
- Rui Ren
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Jie Gao
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Dongmei Yin
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Kai Li
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China
| | - Chuqiao Lu
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Sagheer Ahmad
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Yonglu Wei
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Jianpeng Jin
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Genfa Zhu
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Fengxi Yang
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
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Ren R, Gao J, Lu C, Wei Y, Jin J, Wong SM, Zhu G, Yang F. Highly Efficient Protoplast Isolation and Transient Expression System for Functional Characterization of Flowering Related Genes in Cymbidium Orchids. Int J Mol Sci 2020; 21:ijms21072264. [PMID: 32218171 PMCID: PMC7177621 DOI: 10.3390/ijms21072264] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 11/16/2022] Open
Abstract
Protoplast systems have been proven powerful tools in modern plant biology. However, successful preparation of abundant viable protoplasts remains a challenge for Cymbidium orchids. Herein, we established an efficient protoplast isolation protocol from orchid petals through optimization of enzymatic conditions. It requires optimal D-mannitol concentration (0.5 M), enzyme concentration (1.2 % (w/v) cellulose and 0.6 % (w/v) macerozyme) and digestion time (6 h). With this protocol, the highest yield (3.50 × 107/g fresh weight of orchid tissue) and viability (94.21%) of protoplasts were obtained from flower petals of Cymbidium. In addition, we achieved high transfection efficiency (80%) through the optimization of factors affecting polyethylene glycol (PEG)-mediated protoplast transfection including incubation time, final PEG4000 concentration and plasmid DNA amount. This highly efficient protoplast-based transient expression system (PTES) was further used for protein subcellular localization, bimolecular fluorescence complementation (BiFC) assay and gene regulation studies of flowering related genes in Cymbidium orchids. Taken together, our protoplast isolation and transfection protocol is highly efficient, stable and time-saving. It can be used for gene function and molecular analyses in orchids and other economically important monocot crops.
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Affiliation(s)
- Rui Ren
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
| | - Jie Gao
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
| | - Chuqiao Lu
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
| | - Yonglu Wei
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
| | - Jianpeng Jin
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
| | - Sek-Man Wong
- Department of Biological Sciences, National University of Singapore (NUS), 14 Science Drive 4, Singapore 117543, Singapore;
- National University of Singapore Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215000, China
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore
| | - Genfa Zhu
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
- Correspondence: (G.Z.); (F.Y.)
| | - Fengxi Yang
- Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; (R.R.); (J.G.); (C.L.); (Y.W.); (J.J.)
- Correspondence: (G.Z.); (F.Y.)
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Lin HY, Chen JC, Fang SC. A Protoplast Transient Expression System to Enable Molecular, Cellular, and Functional Studies in Phalaenopsis orchids. FRONTIERS IN PLANT SCIENCE 2018; 9:843. [PMID: 29988409 PMCID: PMC6024019 DOI: 10.3389/fpls.2018.00843] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/30/2018] [Indexed: 05/24/2023]
Abstract
The enigmatic nature of the specialized developmental programs of orchids has fascinated plant biologists for centuries. The recent releases of orchid genomes indicate that orchids possess new gene families and family expansions and contractions to regulate a diverse suite of developmental processes. However, the extremely long orchid life cycle and lack of molecular toolkit have hampered the advancement of orchid biology research. To overcome the technical difficulties and establish a platform for rapid gene regulation studies, in this study, we developed an efficient protoplast isolation and transient expression system for Phalaenopsis aphrodite. This protocol was successfully applied to protein subcellular localization and protein-protein interaction studies. Moreover, it was confirmed to be useful in delineating the PaE2F/PaDP-dependent cell cycle pathway and studying auxin response. In summary, the established orchid protoplast transient expression system provides a means to functionally characterize orchid genes at the molecular level allowing assessment of transcriptome responses to transgene expression and widening the scope of molecular studies in orchids.
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Affiliation(s)
- Hsiang-Yin Lin
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Jhun-Chen Chen
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Su-Chiung Fang
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
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Eeckhaut T, Lakshmanan PS, Deryckere D, Van Bockstaele E, Van Huylenbroeck J. Progress in plant protoplast research. PLANTA 2013; 238:991-1003. [PMID: 23955146 DOI: 10.1007/s00425-013-1936-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 07/18/2013] [Indexed: 06/02/2023]
Abstract
In this review we focus on recent progress in protoplast regeneration, symmetric and asymmetric hybridization and novel technology developments. Regeneration of new species and improved culture techniques opened new horizons for practical breeding in a number of crops. The importance of protoplast sources and embedding systems is discussed. The study of reactive oxygen species effects and DNA (de)condensation, along with thorough phytohormone monitoring, are in our opinion the most promising research topics in the further strive for rationalization of protoplast regeneration. Following, fusion and fragmentation progress is summarized. Genomic, transcriptomic and proteomic studies have led to better insights in fundamental processes such as cell wall formation, cell development and chromosome rearrangements in fusion products, whether or not obtained after irradiation. Advanced molecular screening methods of both genome and cytoplasmome facilitate efficient screening of both symmetric and asymmetric fusion products. We expect that emerging technologies as GISH, high resolution melting and next generation sequencing will pay major contributions to our insights of genome creation and stabilization, mainly after asymmetric hybridization. Finally, we demonstrate agricultural valorization of somatic hybridization through enumerating recent introgression of diverse traits in a number of commercial crops.
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Affiliation(s)
- Tom Eeckhaut
- Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Applied Genetics and Breeding, Caritasstraat 21, 9090, Melle, Belgium.
| | - Prabhu Shankar Lakshmanan
- Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Applied Genetics and Breeding, Caritasstraat 21, 9090, Melle, Belgium
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000, Ghent, Belgium
| | - Dieter Deryckere
- Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Applied Genetics and Breeding, Caritasstraat 21, 9090, Melle, Belgium
| | - Erik Van Bockstaele
- Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Applied Genetics and Breeding, Caritasstraat 21, 9090, Melle, Belgium
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000, Ghent, Belgium
| | - Johan Van Huylenbroeck
- Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Applied Genetics and Breeding, Caritasstraat 21, 9090, Melle, Belgium
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The role of activated charcoal in plant tissue culture. Biotechnol Adv 2008; 26:618-31. [PMID: 18786626 DOI: 10.1016/j.biotechadv.2008.08.003] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 08/01/2008] [Accepted: 08/01/2008] [Indexed: 11/23/2022]
Abstract
Activated charcoal has a very fine network of pores with large inner surface area on which many substances can be adsorbed. Activated charcoal is often used in tissue culture to improve cell growth and development. It plays a critical role in micropropagation, orchid seed germination, somatic embryogenesis, anther culture, synthetic seed production, protoplast culture, rooting, stem elongation, bulb formation etc. The promotary effects of AC on morphogenesis may be mainly due to its irreversible adsorption of inhibitory compounds in the culture medium and substancially decreasing the toxic metabolites, phenolic exudation and brown exudate accumulation. In addition to this activated charcoal is involved in a number of stimulatory and inhibitory activities including the release of substances naturally present in AC which promote growth, alteration and darkening of culture media, and adsorption of vitamins, metal ions and plant growth regulators, including abscisic acid and gaseous ethylene. The effect of AC on growth regulator uptake is still unclear but some workers believe that AC may gradually release certain adsorbed products, such as nutrients and growth regulators which become available to plants. This review focuses on the various roles of activated charcoal in plant tissue culture and the recent developments in this area.
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