Somatic embryogenesis (SE) in conifers: a powerful research tool and a method to capture genetic gains from the breeding programs

Egertsdotter 1150 766

Somatic embryogenesis (SE) is an in vitro based clonal propagation method that can be used as a model system for research, or for multiplication of valuable seeds of commercial value or for conservation of threatened species.

In order to meet the demands on future forests for higher productivity and also for higher adaptability to climate change, it is necessary to capture the genetic gains from the breeding programs. This can only be done by large-scale clonal propagation of elite trees selected from the breeding programs.

For spruce and other conifers, somatic embryogenesis (SE) is the only method that has the potential for clonal propagation to sufficiently large numbers of elite trees for commercial planting.

UE ny bild3The process steps of somatic embryogenesis (SE) in conifers

Cost effective SE-plant production requires automated methods. Such methods have been demonstrated on a pilot scale for Swedish forestry operations.

In the UPSC SE lab, we have an automated instrument based on the same key technology utilized in the pilot system for SE plant production (the SE Fluidics System). The instrument is a valuable tool in fundamental research projects to study embryo development. It can perform dispersion, separation/singulation, image analysis and selection of plant propagules such as somatic embryos.

Picture UE 1920The R&D SE Fluidics System is mainly used for singulation and harvest of mature somatic embryos (system overview in A). Mature somatic embryos are produced in liquid medium in a temporary immersion bioreactor system (B) where hundreds to thousands of mature embryos are produced in each bioreactor (C: top view into bioreactor), or on solid medium in a petri plate (E). After processing in the Fluidics system, singulated mature embryos are analyzed by image analysis (D) and selected based on the pre-programmed selection criteria for embryos with good chances to form a plant (F).

Our research interest is to understand and explain the different processes that regulate development of conifer embryos into early-stage plants. We utilize somatic embryogenesis as a model system to study how metabolic processes are required and regulated during embryo development. By studying the nutritional requirements of the embryo during development and the correlated active cellular processes, we have found that nitrogen utilization appears to be regulated over the course of embryo development with the earlier embryo stages benefiting from a supply of organic nitrogen such as glutamine (Dahrendorf et al. 2018). During later stages of embryo development, our results indicate the importance of desiccation tolerance and suggest key functions for different types of carbohydrates (Businge et al. 2013). Key metabolic events during shoot and root apical meristem formation are associated with morphological events during early plant formation (Dobrowolska et al. 2016).

sweden_greySvensk sammanfattning

Publication list

  1. Evaluation of parameters to characterise germination-competent mature somatic embryos of Norway spruce (Picea abies)
    Biosystems Engineering 2021, 203:55-59
  2. Plant physiological and genetical aspects of the somatic embryogenesis process in conifers
  3. Using Norway spruce clones in Swedish forestry: implications of clones for management
  4. Using Norway spruce clones in Swedish forestry: introduction
  5. Automation and Scale Up of Somatic Embryogenesis for Commercial Plant Production, With Emphasis on Conifers
  6. Improved and synchronized maturation of Norway spruce (Picea abies (L.) H.Karst.) somatic embryos in temporary immersion bioreactors
    In Vitro Cell Dev Biol Plant. 2018, 54(6):612-620
  7. Nitrogen utilization during germination of somatic embryos of Norway spruce: revealing the importance of supplied glutamine for nitrogen metabolism
    Trees 2018, 33(2):383-394
  8. Analysis of Nitrogen Utilization Capability during the Proliferation and Maturation Phases of Norway Spruce (Picea abies (L.) H.Karst.) Somatic Embryogenesis
    FORESTS 2018, 9 (6)
  9. SE Fluidics System
    In: Jain SM, Gupta P(eds) Step Wise Protocols for Somatic Embryogenesisof Important Woody Plants.
    2018, Volume 1, second edition, Forestry Sciences 84. Springer International Publishing AG. Cham, Switzerland. p. 211-227.
  10. Plant physiological and genetical aspects of the somatic embryogenesis process in conifers
    Scand. J. For. Res. 2018 
  11. Metabolome and transcriptome profiling reveal new insights into somatic embryo germination in Norway spruce (Picea abies)
    Tree Physiol. 2017; 37 (12):1752-1766
  12. Nitrogen uptake and assimilation in proliferating embryogenic cultures of Norway spruce-Investigating the specific role of glutamine
    PLoS One. 2017, 12(8):e0181785 eCollection 2017
  13. Evaluation of a New Temporary Immersion Bioreactor System for Micropropagation of Cultivars of Eucalyptus, Birch and Fir
    FORESTS 2017, 8 (6)
  14. DNA methylome of the 20-gigabase Norway spruce genome
    Proc Natl Acad Sci U S A. 2016, 113 (50):E8106-E8113
  15. Histological analysis reveals the formation of shoots rather than embryos in regenerating cultures of Eucalyptus globulus
    Plant Cell, Tissue and Organ Culture, 2017 128 (2):319-326
  16. Fraser fir somatic embryogenesis: high frequency initiation, maintenance, embryo development, germination and cryopreservation
    NEW FORESTS 2016, 47(3):453-480
  17. Bioreactor technology for clonal propagation of plants and metabolite production
    FRONTIERS IN BIOLOGY (2015) 10:177
  18. A possible biochemical basis for fructose-induced inhibition of embryo development in Norway spruce (Picea abies)
    Tree Physiol. 2014; 34(6):657-69
  19. Close to the application of somatic embryogenesis
    News and Views, Scandinavian Journal of Forest Research (2014) 29, 615-616
  20. The effect of carbohydrates and osmoticum on storage reserve accumulation and germination of Norway spruce somatic embryos
    Physiol Plant. 2013; 149(2):273-285
  21. Metabolite profiling reveals clear metabolic changes during somatic embryo development of Norway spruce (Picea abies)
    Tree Physiol. 2012 , 32(2):232-244
  22. Comparison of gene expression markers during zygotic and somatic embryogenesis in pine
    In Vitro Cell.Dev.Biol.-Plant (2012) 48:341
  23. A possible biochemical basis for fructose-induced inhibition of embryo development in Norway spruce (Picea abies)
    Tree Physiol. 2011; 31(52): 539-554
  24. Possible effect from shear stress on maturation of somatic embryos of Norway spruce (Picea abies)
    Biotechnol. Bioeng. 2011, 109 (5), 1089-99
  25. Effects from shear stress on morphology and growth of early stages of Norway spruce somatic embryos
    Biotechnol. Bioeng. 2010; 105: 588–599
  26. Identification and characterization of a matrix metalloproteinase (Pta1-MMP) expressed during Loblolly pine (Pinus taeda) seed development, germination completion, and early seedling establishment
    Planta 2009; 230(2): 339- 354
  27. Lignin biosynthesis in transgenic Norway spruce plants harboring antisense constructs of cinnamoyl CoA reductase (CCR)
    Transgenic Res. 2008, 17: 379 
  28. Effect of fluid shear stress on endocytosis of heparan sulphate and low density lipoproteins
    J. Biomed. Biotechn. 2007, Article ID 65136, 8 pages,
  29. Comparison of standard exponential and linear techniques to amplify small cDNA samples for microarrays
    BMC Genomics 2005, 6:61;
  30. Somatic embryogenesis for plant production of Abies lasiocarpa
    Canadian Journal of Forest Research 2005, 35(5): 1053-1060,
  31. Gene Expression during Formation of Earlywood and Latewood in Loblolly Pine: Expression Profiles of 350 Genes
    Plant biol (Stuttg) 2004; 6(6): 654-663;
  32. Variation in transcript abundance during somatic embryogenesis in gymnosperms
    Tree Phys. 2004, 24, 1073-1085
  33. Photosynthetic Acclimation Is Reflected in Specific Patterns of Gene Expression in Drought-Stressed Loblolly Pine
    Plant Physiology Dec 2003, 133 (4) 1702-1716; DOI: 10.1104/pp.103.026914
  34. Transcript profiles of stress-related genes in developing white spruce (Picea glauca) somatic embryos cultured with polyethylene glycol
    Plant Sci 2003, 165(4), 719-729,
  35. Analysis of lignin produced by cinnamyl alcohol dehydrogenase-deficient Pinus taeda cultured cells
    Plant Phys. Biochem. 2003, 41(5), 439-445,
  36. The Effects of Polyethylene Glycol on Gene Expression of Developing White Spruce Somatic Embryos
    Plant Phys. 2003, 131 (1) 49-60; DOI: 10.1104/pp.015214 
  37. A promoter from the loblolly pine PtNIP1;1 gene directs expression in an early-embryogenesis and suspensor-specific fashion
    Planta 2002, 215(4), 694-698,
  38. Heterologous Array Analysis in Pinaceae: Hybridization of Pinus taeda cDNA Arrays with cDNA from Needles and Embryogenic Cultures of P. taeda, P. sylvestris or Picea abies
    Comparative and Functional Genomics 2002, 3(4), 306-318,
  39. Somatic embryogenesis in Picea suspension cultures
    1998, In Plant Cell Culture Protocols. Ed. R. Hall, Totowa, Humana Press, ISBN 0-89603-549-2
  40. Development of somatic embryos in Norway spruce
    J. Exp. Bot. 1998, 49(319), 155-162,
  41. Somatic embryogenesis in conifers - A case study of induction and development of somatic embryos in Picea abies
    Plant Growth Regulation 1996, 20: 3-9,
  42. Regulation of somatic embryo development in Norway spruce (Picea abies)
    Agronomie 1996, 16:603-608,
  43. Secretion of Specific Extracellular Proteins by Somatic Embryos of Picea abies is Dependent on Embryo Morphology
    Ann. Bot. 1996, 77, 143-152,
  44. Abscisic acid-induced secretion of an antifreeze-like protein in embryogenic cell lines of Picea abies
    J Plant Physiol. 1996, 149, 163-170,
  45. Somatic embryogenesis in Norway spruce (Picea abies)
    1995, In Biotechnology in Agriculture and Forestry. Vol. 30: Somatic embryogenesis and synthetic seeds I”. Ed. Y. P. S. Bajaj, Springer-Verlag Berlin, Heidelberg. ISBN 3-540-57448-4
  46. Somatic embryogenesis in Norway spruce (Picea abies)
    1995, In Somatic embryogenesis in woody plants. Vol. 3. Eds. S. Mohan Jain, P. K. Gupta and R. J. Newton, Kluwer Academic Publishers, Dordrecht. ISBN 0-7923-2938-4
  47. Importance of arabinogalactan proteins for the development of somatic embryos of Norway spruce (Picea abies)
    Physiol. Plant. 1995, 93, 334-345,
  48. Extracellular proteins in embryogenic suspension cultures of Norway spruce (Picea abies)
    Physiol. Plant. 1993, 88, 315-321,
  49. Classification of Embryogenic Cell-lines of Picea abies as Regards Protoplast Isolation and Culture
    J Plant Phys. 1993, 141(2), 222-229,