Methods for producing a synchronized population of conifer somatic embryos

A method for producing a synchronized population of pine somatic embryos, the method comprising:

• (a) cultivating pre-cotyledonary pine embryogenic cells in, or on a maintenance medium comprising nutrients that sustain the pine embryogenic cells;
• (b) cultivating pre-cotyledonary pine embryogenic cells from step (a) for a period from one week to two weeks in, or on, a synchronization medium that comprises maltose as the principal metabolizable sugar source, an absorbent composition and at least one synchronization agent selected from the group consisting of abscisic acid and a gibberellin, wherein the absorbent composition and the at least one synchronization agent are present at a concentration effective to produce a synchronized population of pre-cotyledonary pine somatic embryos wherein at least 50% of the pre-cotyledonary pine somatic embryos in the synchronized population are at the same developmental stage;
• and
• (c) transferring the synchronized population of pre-cotyledonary pine somatic embryos from step (b) to a development medium and culturing the pre-cotyledonary pine somatic embryos for a period from 9 to 14 weeks to produce a synchronized population of cotyledonary pine somatic embryos.