Clonal propagation of conifers by somatic embryogenesis (SE) – an introduction to methodology and examples of applications for research and plant production

Authors

  • Josefine Björs Swedish University of Agricultural Sciences
  • Amelia Tudoran Swedish University of Agricultural Sciences
  • Daniel Gräns Swedish University of Agricultural Sciences
  • Andreas Helmersson The Forest Research Institute of Sweden (Skogforsk)
  • Adriana Puentes Swedish University of Agricultural Sciences
  • Elisabeth Wallin Swedish University of Agricultural Sciences
  • Ulrik Brauner Nilsen University of Copenhagen
  • Ulrika Egertsdotter Swedish University of Agricultural Sciences

DOI:

https://doi.org/10.21750/REFOR.20.02.128

Keywords:

Somatic embryogenesis, Conifer, Methodology, Applications, Initiation

Abstract

This article is aimed as a basic introduction to conifer somatic embryogenesis for someone with a general interest in applications of this technique and/or who is interested in starting some practical work in the field. We also present data from an example study on individual trees’ ability to initiate somatic embryogenesis in Norway spruce (Picea abies). A total of 158 trees were each tested for ability and relative competence to initiate somatic embryogenesis from the zygotic embryos by observing the initiation frequency for ten zygotic embryos from each individual tree.  Furthermore, we conducted a case study by following the process for SE plant formation for a selection of 48 cell lines that were monitored through the SE developmental pathway, with data collected on the success rates at different steps. We then evaluated the relative importance of different steps for the outcome of plant formation and yield.

Downloads

Download data is not yet available.

Author Biographies

  • Josefine Björs, Swedish University of Agricultural Sciences

    Dept. of Forest Genetics and Plant Physiology

    M.Sc. student

  • Amelia Tudoran, Swedish University of Agricultural Sciences

    Dept. of Forest Mycology and Plant Pathology

    Ph.D. student

     

  • Daniel Gräns, Swedish University of Agricultural Sciences

    School for Forest Management

    Senior lecturer 

  • Andreas Helmersson, The Forest Research Institute of Sweden (Skogforsk)

    The Forest Research Institute of Sweden (Skogforsk)

    Senior researcher

  • Adriana Puentes, Swedish University of Agricultural Sciences

    Dept. of Ecology

    Associate professor

  • Elisabeth Wallin, Swedish University of Agricultural Sciences

    School for Forest Management

    Department Chair

  • Ulrik Brauner Nilsen, University of Copenhagen

    Dept. of Geosciences and Natural Resource Management

    Professor

  • Ulrika Egertsdotter, Swedish University of Agricultural Sciences

    Umeå Plant Science Centre, Dept. of Forest Genetics and Plant Physiology

    Professor

References

Anderegg WRL, Chegwidden OS, Badgley G, Trugman AT, Cullenward D, Abatzoglou JT, Hicke JA, Freeman J, Hamman JJ (2022) Future climate risks from stress, insects and fire across US forests. Lawler J (ed.) Ecol Lett 25 (6): 1510-1520. https://doi.org/10.1111/ele.14018 DOI: https://doi.org/10.1111/ele.14018

Arnold SV, Clapham D (2008) Spruce Embryogenesis. In: Suárez MF and Bozhkov PV (eds) Plant Embryogenesis. Humana Press: 31-47. https://doi.org/10.1007/978-1-59745-273-1_3 DOI: https://doi.org/10.1007/978-1-59745-273-1_3

Baison J, Vidalis A, Zhou L, Chen Z, Li Z, Sillanpää MJ, Bernhardsson C, Scofield D, Forsberg N, Grahn T, Olsson L, Karlsson B, Wu H, Ingvarsson PK, Lundqvist S, Niittylä T, García‐Gil MR (2019) Genome‐wide association study identified novel candidate loci affecting wood formation in Norway spruce. The Plant Journal 100 (1): 83-100. https://doi.org/10.1111/tpj.14429 DOI: https://doi.org/10.1111/tpj.14429

Berggren K, Nordkvist M, Björkman C, Bylund H, Klapwijk MJ, Puentes A (2023) Synergistic effects of methyl jasmonate treatment and propagation method on Norway spruce resistance against a bark-feeding insect. Front Plant Sci 14: 1165156. https://doi.org/10.3389/fpls.2023.1165156 DOI: https://doi.org/10.3389/fpls.2023.1165156

Berggren K, Tudoran A, Chen Y, Tikkinen M, Bylund H, Björkman C, Egertsdotter U, Puentes A (2025) Effects of propagation method and methyl jasmonate treatment on stem bark wound healing in Norway spruce seedlings. European Journal of Forest Research. https://doi.org/10.1007/s10342-025-01795-0 DOI: https://doi.org/10.1007/s10342-025-01795-0

Björs J, Sjögren J (2023) Differences in somatic embryogenesis initiation rates between individual trees of Norway spruce. (BSc Thesis). Swedish University of Agricultural Sciences. http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-18587

Chakraborty D Ciceu A, Ballian D, Benito Garzón M, Bolte A, Bozic G, Buchacher R, Čepl J, Cremer E, Ducousso A, Gaviria J, George JP, Hardtke A, Ivankovic M, Klisz M, Kowalczyk J, Kremer A, Lstibůrek M, Longauer R, Mihai G, Nagy L, Petkova K, Popov E, Schirmer R, Skrøppa T, Solvin TM, Steffenrem A, Stejskal J, Stojnic S, Volmer K, Schueler S (2024). Assisted tree migration can preserve the European forest carbon sink under climate change. Nature Climate Change 14 (8): 845-852. https://doi.org/10.1038/s41558-024-02080-5 DOI: https://doi.org/10.1038/s41558-024-02080-5

Chen Z-Q, Zan Y, Milesi P, Zhou L, Chen J, Li L, Cui B, Niu S, Westin J, Karlsson B, García-Gil MR, Lascoux M, Wu HX (2021) Leveraging breeding programs and genomic data in Norway spruce (Picea abies L. Karst) for GWAS analysis. Genome Biology 22 (1): 179. https://doi.org/10.1186/s13059-021-02392-1 DOI: https://doi.org/10.1186/s13059-021-02392-1

Christensen C (2024) The European Christmas tree market in numbers. Proceedings from the 16th International Christmas Tree Research and Extension conference. 2

Cui Y, Zhao J, Gao Y, Zhao R, Zhang J, Kong L (2021) Efficient Multi-Sites Genome Editing and Plant Regeneration via Somatic Embryogenesis in Picea glauca. Front Plant Sci 12: 751891. https://doi.org/10.3389/fpls.2021.751891 DOI: https://doi.org/10.3389/fpls.2021.751891

Dobrowolska I, Businge E, Abreu IN, Moritz T, Egertsdotter U (2017) Metabolome and transcriptome profiling reveal new insights into somatic embryo germination in Norway spruce (Picea abies). Tree Physiology 37 (12): 1752-1766. https://doi.org/10.1093/treephys/tpx078 DOI: https://doi.org/10.1093/treephys/tpx078

Domke GM, Fettig CJ, Marsh AS, Baumflek M, Gould WA, Halofsky JE, Joyce LA, LeDuc SD, Levinson DH, Littell JS, Miniat CF, Mockrin MH, Peterson DL, Prestemon J, Sleeter BM, Swanston C, Crimmins AR, Avery CW, Easterling DR, Kunkel KE, Stewart BC, Maycock TK (2023) Chapter 7 : Forests. Fifth National Climate Assessment. U.S. Global Change Research Program. https://doi.org/10.7930/NCA5.2023.CH7 DOI: https://doi.org/10.7930/NCA5.2023.CH7

Egertsdotter U (2019) Plant physiological and genetical aspects of the somatic embryogenesis process in conifers. Scandinavian Journal of Forest Research 34: 360-369. https://doi.org/10.1080/02827581.2018.1441433 DOI: https://doi.org/10.1080/02827581.2018.1441433

Egertsdotter U, Ahmad I, Clapham D (2019) Automation and Scale Up of Somatic Embryogenesis for Commercial Plant Production, With Emphasis on Conifers. Front Plant Sci 10: 109. https://doi.org/10.3389/fpls.2019.00109 DOI: https://doi.org/10.3389/fpls.2019.00109

El-Kassaby YA, Thomson AJ (1996) Parental Rank Changes Associated with Seed Biology and Nursery Practices in Douglas-Fir. Forest Science 42 (2): 228-235. https://doi.org/10.1093/forestscience/42.2.228 DOI: https://doi.org/10.1093/forestscience/42.2.228

Eriksson G (1973) Flowering in a clone trial of Picea abies Karst.

Fehér A (2006) Why Somatic Plant Cells Start to form Embryos? In: Mujib A and Šamaj J (eds.) Somatic Embryogenesis. Springer-Verlag. 85-101. https://doi.org/10.1007/7089_019 DOI: https://doi.org/10.1007/7089_019

Find J (2016) Towards industrial production of tree varieties through somatic embryogenesis and other vegetative propagation technologies: Nordmanns fir (Abies nordmanniana (Steven) Spach) -From research laboratory to production. In: Vegetative Propagation of Forest Trees. National Institute of Forest Science (NIFoS). 528-537. [2025-09-18]

Find J, Grace L, Krogstrup P (2002) Effect of anti‐auxins on maturation of embryogenic tissue cultures of Nordmanns fir (Abies nordmanniana). Physiologia Plantarum 116 (2): 231-237. https://doi.org/10.1034/j.1399-3054.2002.1160213.x DOI: https://doi.org/10.1034/j.1399-3054.2002.1160213.x

Funda T, El-Kassaby YA (2012) Seed orchard genetics. CABI Reviews: 1-23. https://doi.org/10.1079/PAVSNNR20127013 DOI: https://doi.org/10.1079/PAVSNNR20127013

Haapanen M, Jansson G, Nielsen Ulrik B, Steffenrem A, Stener L-G (2015) The status of tree breeding and its potential for improving biomass production: A review of breeding activities and genetic gains in Scandinavia and Finland. SkogForsk.

Högberg K-A, Ekberg I, Norell L, von Arnold S (1998) Integration of somatic embryogenesis in a tree breeding programme: a case study with Picea abies. Canadian Journal of Forest Research 28 (10): 1536-1545. https://doi.org/10.1139/x98-137 DOI: https://doi.org/10.1139/x98-137

Jain SM, Gupta P (eds) (2018) Step Wise Protocols for Somatic Embryogenesis of Important Woody Plants: Volume I. Springer International Publishing. https://doi.org/10.1007/978-3-319-89483-6 DOI: https://doi.org/10.1007/978-3-319-89483-6

Jin F, Hu L, Yuan D, Xu J, Gao W, He L, Yang X, Zhang X (2014) Comparative transcriptome analysis between somatic embryos ( SE s) and zygotic embryos in cotton: evidence for stress response functions in SE development. Plant Biotechnology Journal 12 (2): 161-173. https://doi.org/10.1111/pbi.12123 DOI: https://doi.org/10.1111/pbi.12123

Klimaszewska K, Hargreaves C, Lelu-Walter M-A, Trontin J-F (2016) Advances in Conifer Somatic Embryogenesis Since Year 2000. In: Germana MA and Lambardi M (eds) In Vitro Embryogenesis in Higher Plants. Springer New York. 131-166. https://doi.org/10.1007/978-1-4939-3061-6_7 DOI: https://doi.org/10.1007/978-1-4939-3061-6_7

Klimaszewska K, Overton C, Stewart D, Rutledge RG (2011) Initiation of somatic embryos and regeneration of plants from primordial shoots of 10-year-old somatic white spruce and expression profiles of 11 genes followed during the tissue culture process. Planta 233 (3): 635-647. https://doi.org/10.1007/s00425-010-1325-4 DOI: https://doi.org/10.1007/s00425-010-1325-4

Krishna H, Alizadeh M, Singh D, Singh U, Chauhan N, Eftekhari M, Sadh RK (2016) Somaclonal variations and their applications in horticultural crops improvement. 3 Biotech 6 (1): 54. https://doi.org/10.1007/s13205-016-0389-7 DOI: https://doi.org/10.1007/s13205-016-0389-7

Kristensen M, Find J, Krogstrup P (n.d.). Micropropagation and Biotechnology in Forestry: Preliminary Results From the Danish Christmas Tree Improvement Programme. In: The International Plant Propagators’ Society Combined Proceedings. International Plant Propagators; Society (IPPS), 4616 25th Avenue NE, PMB 582, Seattle, Washington 1. 315-320.

Kvaalen H, Johnsen Ø (2008) Timing of bud set in Picea abies is regulated by a memory of temperature during zygotic and somatic embryogenesis. New Phytologist 177 (1): 49-59. https://doi.org/10.1111/j.1469-8137.2007.02222.x DOI: https://doi.org/10.1111/j.1469-8137.2007.02222.x

Lindgren D, Gea L, Jefferson P (1996) Loss of Genetic Diversity Monitored by Status Number.

Lobo A, Iver Find J, Kehlet Hansen J, Ræbild A, Dahl Kjær E (2022) Effect of temperature and osmotic stress during somatic embryogenesis on phenology and physiology of abies nordmanniana emblings. Forest Ecol Manag 514: 120212. https://doi.org/10.1016/j.foreco.2022.120212 DOI: https://doi.org/10.1016/j.foreco.2022.120212

Lstibůrek M, García‐Gil MR, Steffenrem A (2023) Rolling front landscape breeding. Annals of Forest Science 80 (1): 36. https://doi.org/10.1186/s13595-023-01203-w DOI: https://doi.org/10.1186/s13595-023-01203-w

Milesi P, Berlin M, Chen J, Orsucci M, Li L, Jansson G, Karlsson B, Lascoux M (2019) Assessing the potential for assisted gene flow using past introduction of Norway spruce in southern Sweden: Local adaptation and genetic basis of quantitative traits in trees. Evolutionary Applications 12 (10): 1946-1959. https://doi.org/10.1111/eva.12855 DOI: https://doi.org/10.1111/eva.12855

Montague MJ, Enns RK, Siegel NR, Jaworski EG (1981) A Comparison of 2,4-Dichlorophenoxyacetic Acid Metabolism in Cultured Soybean Cells and in Embryogenic Carrot Cells. Plant Physiology 67 (4): 603-607. https://doi.org/10.1104/pp.67.4.603 DOI: https://doi.org/10.1104/pp.67.4.603

Nielsen UB, Hansen CB, Hansen U, Johansen VK, Egertsdotter U (2022) Accumulated effects of factors determining plant development from somatic embryos of Abies nordmanniana and Abies bornmuelleriana. Front Plant Sci 13, 989484. https://doi.org/10.3389/fpls.2022.989484 DOI: https://doi.org/10.3389/fpls.2022.989484

Nielsen UB, Xu J, Hansen OK (2020) Genetics in and opportunities for improvement of Nordmann fir (Abies nordmanniana (Steven) Spach) Christmas tree production. https://link.springer.com/10.1007/s11295-020-01461-z [2025-09-11] DOI: https://doi.org/10.1007/s11295-020-01461-z

Norgaard, J. & Krogstrup, P. (1991). Cytokinin induced somatic embryogenesis from immature embryos of Abies nordmanniana Lk. Plant Cell Reports, 9 (9). https://doi.org/10.1007/BF00232107 DOI: https://doi.org/10.1007/BF00232107

Nørgaard JV (1997) Somatic embryo maturation and plant regeneration in Abies nordmanniana Lk. Plant Science 124 (2), 211-221. https://doi.org/10.1016/S0168-9452(97)04614-1 DOI: https://doi.org/10.1016/S0168-9452(97)04614-1

Norgaard JV, Baldursson S, Krogstrup P (1993) Genotypic differences in the ability of embryogenic Abies nordmannia cultures to survive cryopreservation. Silvae Genetica 42 (2-3): 93-97.

Nørgaard JV, Krogstrup P (1995) Somatic Embryogenesis in Abies spp. In: Jain SM, Gupta PK, Newton RJ (eds.) Somatic Embryogenesis in Woody Plants. Springer Netherlands. 341-355. https://doi.org/10.1007/978-94-011-0960-4_21 DOI: https://doi.org/10.1007/978-94-011-0960-4_21

Pâques LE (ed.) (2013) Forest Tree Breeding in Europe: Current State-of-the-Art and Perspectives. Springer Netherlands. https://doi.org/10.1007/978-94-007-6146-9 DOI: https://doi.org/10.1007/978-94-007-6146-9

Park Y-S, Bonga JM, Moon H-K (2016) An industrial perspective on the use of advanced reforestation stock technologies. Vegetative Propagation of Forest Trees. National Institute of Forest Science (NIFoS). Seoul, Korea, pp 323-334.

Peterson DL, Vose JM, Domke GM, Fettig CJ, Joyce L, Keane RE, Luce CH, Prestemon JP (2018) Chapter 6 : Forests. Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II. U.S. Global Change Research Program. https://doi.org/10.7930/NCA4.2018.CH6 DOI: https://doi.org/10.7930/NCA4.2018.CH6

Poovaiah C, Phillips L, Geddes B, Reeves C, Sorieul M, Thorlby G (2021) Genome editing with CRISPR/Cas9 in Pinus radiata (D. Don). BMC Plant Biology 21 (1): 363. https://doi.org/10.1186/s12870-021-03143-x DOI: https://doi.org/10.1186/s12870-021-03143-x

Puentes A, Högberg K-A, Björklund N, Nordlander G (2018) Novel Avenues for Plant Protection: Plant Propagation by Somatic Embryogenesis Enhances Resistance to Insect Feeding. Front Plant Sci 9: 1553. https://doi.org/10.3389/fpls.2018.01553 DOI: https://doi.org/10.3389/fpls.2018.01553

Puentes A, Zhao T, Lundborg L, Björklund N, Borg-Karlson A-K (2021) Variation in Methyl Jasmonate-Induced Defense Among Norway Spruce Clones and Trade-Offs in Resistance Against a Fungal and an Insect Pest. Front Plant Sci 12: 678959. https://doi.org/10.3389/fpls.2021.678959 DOI: https://doi.org/10.3389/fpls.2021.678959

Pullman GS, Bucalo K (2011) Pine Somatic Embryogenesis Using Zygotic Embryos as Explants. In: Thorpe TA and Yeung EC (eds.) Plant Embryo Culture. Humana Press. 267-291. https://doi.org/10.1007/978-1-61737-988-8_19 DOI: https://doi.org/10.1007/978-1-61737-988-8_19

Pullman GS, Buchanan M (2003) Loblolly pine (Pinus taeda L.): stage-specific elemental analyses of zygotic embryo and female gametophyte tissue. Plant Science 164 (6): 943-954. https://doi.org/10.1016/S0168-9452(03)00080-3 DOI: https://doi.org/10.1016/S0168-9452(03)00080-3

Pullman GS, Webb DT (1994) An Embryo Staging System for Comparison of Zygotic and Somatic Embryo Development. https://repository.gatech.edu/server/api/core/bitstreams/10546bb8-8fc5-4e58-8059-579fb0e952aa/content

Rosvall O, Lindgren D, Mullin TJ (1998) Sustainability robustness and efficiency of a multi-generation breeding strategy based on within-family clonal selection. Silvae Genetica 47(5-6): 307-321. https://www.researchgate.net/publication/228608799_Sustainability_robustness_and_efficiency_of_a_multi-generation_breeding_strategy_based_on_within-family_clonal_selection#full-text [2025-07-28]

Sandberg M (2023) Finding Genotype-Phenotype Correlations in Norway Spruce - A Genome-Wide Association Study using Machine Learning. (MSc Thesis). Umeå University. https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-209837 [2025-07-28]

Sarmast MK (2018) In vitro propagation of conifers using mature shoots. Journal of Forestry Research 29 (3): 565-574. https://doi.org/10.1007/s11676-018-0608-7 DOI: https://doi.org/10.1007/s11676-018-0608-7

Sarmast MK, Ghaleh ZR, Alizadeh M (2024) Somaclonal Variation in Conifers. In: Sánchez-Romero C (ed.) Somaclonal Variation: Basic and Practical Aspects. Springer International Publishing. 123-142. https://doi.org/10.1007/978-3-031-51626-9_7 DOI: https://doi.org/10.1007/978-3-031-51626-9_7

Tikkinen M, Varis S, Aronen T (2018) Development of Somatic Embryo Maturation and Growing Techniques of Norway Spruce Emblings towards Large-Scale Field Testing. Forests 9 (6): 325. https://doi.org/10.3390/f9060325 DOI: https://doi.org/10.3390/f9060325

Trontin J-F, Sow MD, Delaunay A, Modesto I, Teyssier C, Reymond I, Canlet F, Boizot N, Le Metté C, Gibert A, Chaparro C, Daviaud C, Tost J, Miguel C, Lelu-Walter M-A, Maury S (2025) Epigenetic memory of temperature sensed during somatic embryo maturation in 2-yr-old maritime pine trees. Plant Physiology 197 (2): kiae600. https://doi.org/10.1093/plphys/kiae600 DOI: https://doi.org/10.1093/plphys/kiae600

UBI (2024) SweTree Technologies expands to complete unique plant pilot project. Umeå Biotech Incubator. https://www.ubi.se/news/swetree-technologies-expands-to-complete-unique-plant-pilot-project/ [2025-09-11]

Varis S, Klimaszewska K, Aronen T (2018) Somatic Embryogenesis and Plant Regeneration From Primordial Shoot Explants of Picea abies (L.) H. Karst. Somatic Trees. Front Plant Sci 9: 1551. https://doi.org/10.3389/fpls.2018.01551 DOI: https://doi.org/10.3389/fpls.2018.01551

Varis S, Tikkinen M, Edesi J, Aronen T (2023) How to Capture Thousands of Genotypes—Initiation of Somatic Embryogenesis in Norway Spruce. Forests 14 (4): 810. https://doi.org/10.3390/f14040810 DOI: https://doi.org/10.3390/f14040810

Wei RP, Lindgren D (1995) Optimal Family Contributions and a Linear Approximation. Theoretical Population Biology 48 (3): 318-332. https://doi.org/10.1006/tpbi.1995.1033 DOI: https://doi.org/10.1006/tpbi.1995.1033

Winkelmann T (2016) Somatic Versus Zygotic Embryogenesis: Learning from Seeds. In: Germana MA and Lambardi M (eds) In Vitro Embryogenesis in Higher Plants. Springer New York. 25-46. https://doi.org/10.1007/978-1-4939-3061-6_2 DOI: https://doi.org/10.1007/978-1-4939-3061-6_2

Xu J, Budde KB, Hansen OK, Thomsen IM, Ravn HP, Nielsen UB (2018a) Do silver fir woolly adelgids (Dreyfusia nordmannianae) facilitate pathogen infestation with Neonectria neomacrospora on Christmas trees (Abies nordmanniana)? Forest Ecol Manag 424: 396-405. https://doi.org/10.1016/j.foreco.2018.05.006 DOI: https://doi.org/10.1016/j.foreco.2018.05.006

Xu J, Nielsen UB (2023) Genetic Variation among Somatic Embryo Clones of Nordmann Fir Grown as Christmas Trees. Forests 14 (2): 279. https://doi.org/10.3390/f14020279 DOI: https://doi.org/10.3390/f14020279

Xu J, Nielsen UB, Hansen OK (2018b) Ad hoc breeding of Abies bornmülleriana for Christmas tree production using a combination of DNA markers and quantitative genetics—a case study. Tree Genetics & Genomes 14 (5): 64. https://doi.org/10.1007/s11295-018-1276-7 DOI: https://doi.org/10.1007/s11295-018-1276-7

Zhao H, Zhang J, Zhao J, Niu S (2024) Genetic transformation in conifers: current status and future prospects. Forestry Research 4 (1), 0-0. https://doi.org/10.48130/forres-0024-0007 DOI: https://doi.org/10.48130/forres-0024-0007

Zhu T, Wang J, Hu J, Ling J (2022) Mini review: Application of the somatic embryogenesis technique in conifer species. Forestry Research 2 (1): 0-0. https://doi.org/10.48130/FR-2022-0018 DOI: https://doi.org/10.48130/FR-2022-0018

Published

2025-12-30

Issue

Section

Articles

How to Cite

Björs, Josefine, Amelia Tudoran, Daniel Gräns, Andreas Helmersson, Adriana Puentes, Elisabeth Wallin, Ulrik Brauner Nilsen, and Ulrika Egertsdotter. “Clonal Propagation of Conifers by Somatic Embryogenesis (SE) – an Introduction to Methodology and Examples of Applications for Research and Plant Production”. REFORESTA, no. 20 (December 30, 2025): 17–40. Accessed January 3, 2026. https://journal.reforestationchallenges.org/index.php/REFOR/article/view/248.