Somatic Embryogenesis in Picea Suspension Cultures
Generation of somatic embryos in spruce is achieved through the execution of five steps designated as: (1) induction of embryogenic tissue, (2) maintenance of embryogenic tissue, (3) embryo development, (4) embryo maturation, and (5) conversion into plants. Depending on species and genotypes within the same species, each step must be optimized for obtaining maximum results. In general, embryogenic tissue is generated from immature and mature zygotic embryos and maintained in either liquid or solid conditions in the presence of plant growth regulators auxin and cytokinin. Initiation of embryo development in suspension cultured is induced by removal of plant growth regulators, whereas continuation of development and completion of maturation require applications of abscisic acid and imposition of a desiccation period. Both treatments are needed for conferring morphological and physiological maturation to the embryos. Mature somatic embryos are germinated in the absence of plant regulators and embryo conversion (i.e., formation of a functional shoot and root, occurs after a few weeks in culture).
Key WordsConversion drying treatment embryogenic tissue embryo development and maturation germination spruce
The author acknowledges with gratitude the support received from the Natural Sciences and Engineering Research Council of Canada in the form of a Discovery Grant.
- 1.Thorpe, T.A. and Stasolla, C. (2001) Somatic embryogenesis, in Current Trends in the Embryology of Angiosperms (Bhojwani, S.S., ed.), Kluwer Acad. Publisher, Dordrecht. pp. 35–64.Google Scholar
- 2.Hosie, R.C. (ed.) (1979) Native Trees of Canada. 8th ed. Fitzhenry and Whiteside, Don Mills.Google Scholar
- 3.Durzan, D.J. (1980) Progress and promise in forest genetics. In: proceedings of the 50th Anniversary Conference, Paper Science and Technology, The Cutting Edge, May 8–10, pp 31–60. The Institute of Paper Chemistry, Appleton, WI.Google Scholar
- 4.Lu, C. Y. and Thorpe, T. A. (1987) Somatic embryogenesis and plantlet regeneration in cultured immature embryos of Picea glauca. J. Plant Physiol. 128, 297–302.Google Scholar
- 11.Joy IV, R.W., Yeung, E.C., Kong, L. and Thorpe, T.A. (1991) Development of white spruce somatic embryos: I. Storage product deposition. In Vitro Cell. Dev. Biol. Plant 27P, 32–41.Google Scholar
- 12.Litvay, J.D., Johnson, M.A., Verma, D., Einspahr, D., and Weyrauch, K. (1985) Conifer suspension culture medium development using analytical data from developing seeds. Institute Paper Chem. Tech. Paper Series 155, Appleton, Wisconsin.Google Scholar
- 17.Kong, L. and Yeung, E.C. (1992) Development of white spruce somatic embryos: II. Continual shoot meristem development during germination. In Vitro Cell. Dev. Biol. Plant 28P, 125–131.Google Scholar
- 22.Kong, L. (1994) Factors affecting white spruce somatic embryogenesis and embryo conversion. Ph.D. Dissertation, University of Calgary, Calgary.Google Scholar