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

Egertsdotter 1150 766The demand for wood and wood-based products is increasing globally.At the same time, the land base available for forest trees is decreasing.The need to improve the productivity of forests is therefore urgent, especially in the northern hemisphere where growth and yields are low compared to southern hemisphere plantation forests. In order to meet the demands on future forests for higher productivity and also for higher adaptability for cli- mate 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 is the only method that has the potential for clonal propagation to su ciently large numbers of Elite trees for planting. For cost e ective SE-plant production, it is however necessary to use au- tomated methods. Such methods has recently been demonstrated to also be bene cial for research purposes and an automated instrument for SE research will soon be available at UPSC.Somatic Embryogenesis (SE) is an in vitro based method that can be used for multiplication of valuable seeds, of commercial value or for conservation purposes. SE is also a valuable tool in fundamental research projects to study embryo development. The basic SE-process of conifers is summarized in the gure.

My research interest is to understand and explain the dif- ferent processes that regulate development of conifer embryos. To establish a basic understanding for the di erent metabolic processes required for ‘normal’ embryo development to take place, we have studied the metabolic pro les of di erent cell lines of Norway spruce that have di erent capacity to develop into plants.The results indicate the importance of desiccation tolerance during the later stages of embryo development, and suggests key functions for di erent types of carbohydrates.To further understand what speci cally a ects the development of somatic embryos in vitro, we have studied the e ects of shear stress that can be sensed by somatic embryos in liquid suspen- sion cultures. We found that it a ects both the earliest stages of multiplication of pro-embryogenic masses and the maturation of embryos, and that the e ect is cell-speci c. This suggests that there are mechanism(s) that can transfer the signal from external mechanical stimuli to the intracellular space.

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Somatic embryogenesis in conifers is started from zygotic embryos (in the seeds). Somatic embryos protrude from the hypocotyl region of the zygotic embryo (ZE) forming a mass of embryogenic culture (EC) in response to auxin and cytokinin. The embryogenic culture can be isolated and will continue to multiply indefinitely when maintained on the same composition culture medium. Maturation of the embryos is induced by ABA. The mature embryos can then germinate and then be transferred to non-sterile conditions for further establishment of a plant..

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Publications list

  1. 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
  2. Nitrogen utilization during germination of somatic embryos of Norway spruce: revealing the importance of supplied glutamine for nitrogen metabolism
    Trees 2018, 09 November, First Online
  3. 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)
  4. Metabolome and transcriptome profiling reveal new insights into somatic embryo germination in Norway spruce (Picea abies)
    Tree Physiol. 2017; 37 (12):1752-1766
  5. 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
  6. Evaluation of a New Temporary Immersion Bioreactor System for Micropropagation of Cultivars of Eucalyptus, Birch and Fir
    FORESTS 2017, 8 (6)
  7. DNA methylome of the 20-gigabase Norway spruce genome
    Proc Natl Acad Sci U S A. 2016, 113 (50):E8106-E8113
  8. 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
  9. Fraser fir somatic embryogenesis: high frequency initiation, maintenance, embryo development, germination and cryopreservation
    NEW FORESTS 2016, 47(3):453-480
  10. A possible biochemical basis for fructose-induced inhibition of embryo development in Norway spruce (Picea abies)
    Tree Physiol. 2014; 34(6):657-69
  11. Businge E, Bygdell J, Wingsle G, Moritz T, Egertsdotter U
    The effect of carbohydrates and osmoticum on storage reserve accumulation and germination of Norway spruce somatic embryos
    Physiol Plant. 2013; 149(2):273-285
  12. Businge E, Brackmann K, Moritz T, Egertsdotter U
    Metabolite profiling reveals clear metabolic changes during somatic embryo development of Norway spruce (Picea abies)
    Tree Physiol. 2012 , 32(2):232-244