In Vitro Propagation of Conifers: Fidelity of the Clonal Offspring
Conifer propagation in vitro is still largely restricted to propagation of juvenile, in most cases embryonic, material. So far, the main method of regeneration has been rooting of adventitious or axillary shoots. However, this method has found little commercial application because, 1) the propagation rates are too low, 2) the cost is too high, and 3) propagation is often not true-to-type. Fortunately, methods have been developed recently to induce somatic embryogenesis in cell cultures derived from embryo expiants. Somatic embryogenesis is better suited for mass propagation than rooting of adventitious or axillary shoots. Therefore, it is anticipated that commercial propagation of juvenile conifer material will soon be possible. Mature trees are far more difficult to clone by in vitro techniques than juvenile specimens. Our work with about 30-year-old Larix decidua trees has resulted in large-scale adventitious shoot formation, but little rooting. Some of the cultures have produced yellow, slimy cell masses which were similar in appearance to embryogenic masses obtained from embryo or megagametophyte explants. They contained bundles of long cells associated with small cells, but none of these developed into recognizable embryos. The potential applications of cloning in vitro in tree improvement schemes are discussed.
KeywordsSugar DMSO Dimethyl Sulfoxide Flushing
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- 8.Franclet, A., Boulay, M., Bekkaoui, F., Fouret, Y., Verschoore-Martouzet, B., and Walker, N., 1987, Rejuvenation, in: Cell and Tissue Culture in Forestry, Vol. 1, General Principles and Biotechnology, J.M. Bonga, and D.J. Durzan, eds., Martinus Nijhoff Publishers, Dordrecht, pp. 232–248.Google Scholar
- 11.Inglis, J.E., 1984, The effects of some growth substances on the promotion and rooting of interfascicular shoots in Pinus caribaea Morelet. Commonw. For. Rev. 63: 115–120.Google Scholar
- 12.Mohammed, G.H., Dunstan, D.I., and Thorpe, T.A., 1986, Influence of nutrient medium upon shoot initiation on vegetative expiants excised from 15- to 18-year-old Picea glauca. N.Z. J. For. Sci. 16: 297–305.Google Scholar
- 13.Norton, M.E., and Norton, C.R., 1986, An alternative to in vitro propagation — axillary shoot enhancement on whole plants. J. Hortic. Sci. 61: 423–428.Google Scholar
- 15.Ritchie, G.A., and Long, A.J., 1986, Field performance of micropropagated Douglas fir. N.Z. J. For. Sci. 16: 343–356.Google Scholar
- 16.Sheffield, E., 1984, Effects of dimethyl sulfoxide on the gametophytic and sporophytic phases of Pteridium aquilinum (L.) Kuhn. Ann. Bot. 54: 531–536.Google Scholar
- 17.Shelbourne, C.J.A., Carson, M.J., and Wilcox, M.D., 1989, New techniques in the genetic improvement of radiata pine. Commonw. For. Rev. 68: 191–201.Google Scholar
- 19.Timmis, R., and Ritchie, G.A., 1988, Epigenetic effects in clonal propagation, in: Proceedings of the Tenth North American Forest Biology Workshop, Vancouver, July 20–22, pp. 12–31.Google Scholar
- 20.Tsogas, M., and Bouriquet, R., 1982, Propagation de l’épicéa par culture in vitro d’embryons et de plantules. Ann. Rech. Sylvicoles, AFOCEL, pp. 345–367.Google Scholar