Abstract: A desiccation-tolerant mature viable gymnosperm somatic embryo is characterized by a moisture content of less than about 55%. Preferably the moisture content is less than about 45%, and for optimal storage capability at freezing temperatures, less than about 36%. The embryo may have a dry weight and per embryo lipid content higher than the lipid content and dry weight of the corresponding gymnosperm zygotic embryo. Preferred desiccation-tolerant gymnosperm somatic embryos are coniferous somatic embryos having a moisture content of less than about 55%.

Abstract: Desiccated mature gymnosperm somatic embryos, preferably coniferous somatic embryos having a moisture content of less than about 55%, are prepared by water stressing immature embryos in a medium comprising a metabolizable carbon source and a suitable growth regulator influencing embryo development, for a period of time and under conditions sufficient to yield mature viable somatic embryos having a moisture content in the specified range. The water stressing should may be environmental, as by controlled declining relative humidity. Or a suitable osmotic or non-osmotic water stress agent can be used. The use of a non-permeating osmotic water stress agent such as polyethylene glycol of molecular weight at least about 1,000 is preferred, in which case the water stress should simulate a non-osmotic water stress. An example of a suitable preferred growth regulator is abscisic acid.

Abstract: A desiccated mature gymnosperm somatic embryo characterized by having a moisture content which is lower than the moisture content of its corresponding zygotic embryo and a dry weight and per embryo lipid content which are higher than the lipid content and dry weight of its corresponding gymnosperm zygotic embryo. Preferred desiccated gymnosperm somatic embryos are conifer somatic embryos having a moisture content ranging between 10 and 55%. Also within the scope of the invention is a method for producing desiccated somatic embryos. The method comprises developing immature embryos in a medium comprising at least one non-permeating water stress agent, a metabolizable carbon source and a growth regulator having an influence on embryo development for a period of time sufficient to yield the recovery of mature somatic embryos having a moisture content which is lower than the moisture content of corresponding zygotic embryos.

Abstract: Conifer somatic embryos can be desiccated to a moisture content below 50%. A moisture content as low as 10% can be produced. The desiccated somatic conifer embryos have greatly increased ability to store lipids and other nutrients as compared to the corresponding zygotic embryo. The embryos are desiccated using a method which requires the utilization of ABA and PEG.