RACEMIC ABSCISIC-ACID AND ABSCISYL ALCOHOL PROMOTE MATURATION OF WHITE SPRUCE (PICEA-GLAUCA) SOMATIC EMBRYOS

Racemic abscisic acid [(+/-)-ABA] and racemic abscisyl alcohol were used to obtain maturation of white spruce (Picea glauca (Moench.) Voss) immature (stage 1) somatic embryos. Data for somatic embryo development were collected between 21 and 70 days after initiation of maturation treatments. The culture period for the maximum production of cotyledonary (stage 3) somatic embryos was approx. 42 days, with either 46-mu-M (+/-)-ABA or 41-mu-M abscisyl alcohol during the first 35 days. Two additional abscisic acid analogues, an acetylenic aldehyde and a dihydroacetylenic alcohol were less effective in promoting somatic embryo maturation. A comparison of the molecular structures of compounds indicated that the presence of an ABA-like side chain with two double bonds was most effective in white spruce somatic embryo maturation. Another factor that influenced the maturation process was the solvent used to dissolve (+/-)-ABA and the analogues. Somatic embryo development could be arrested at stage 3 by extending exposure to 60-mu-M (+/-)-ABA for up to 9 weeks. Germination resulted after removal of (+/-)-ABA.