Method for reproducing coniferous plants by somatic embryogenesis

Abstract

The present invention is a method for reproducing coniferous trees by somatic embryogenesis using plant tissue culture techniques. The method comprises a multistage culturing process. A suitable explant, typically the fertilized embryo excised from a mature or immature seed, is first cultured on a medium that induces multiple early stage proembryos. Preferably the proembryos from the indication stage are further multiplied in a second culture having reduced growth hormones. The early stage proembryos are then placed in or on a late stage proembryo development culture having a significantly higher osmotic potential than the previous stage or stages. This increased osmotic potential medium is a critical key to the development of very robust late stage proembryos having at least about 100 cells and multiple suspensor cells. Culturing from this point coninues in an embryo development medium very low in or lacking growth hormones but containing abscisic acid. After a period of several weeks cotyledonary embryos will have formed. These have a well defined bipolar structure with cotyledonary primordia at one end and a latent radicle at the other. Culturing to this point is carried out in darkness or greatly subdued light. The cotyledonary embryos are then transferred to a growth medium with a light/dark photoperiod for development of plantlets. The plantlets may then be transplanted to soil for further growth. The method has been successful with a broad range of species and with numerous genotypes that could not previously be propagated by embryogenesis.