SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION FROM ZYGOTIC EMBRYO CULTURE IN BLUE SPRUCE (PICEA-PUNGENS ENGELMAN)

Somatic embryogenesis and plantlet formation have been achieved from cultured mature zygotic embryos of blue spruce (Picea pungens Engelman.). The effect of three basal media LP, LM, and BLG, all used at half-strength, was tested at the induction phase. LM medium induced somatic embryogenesis to a higher extent than LP whereas BLG did not produce any embryonal-suspensor mass representing stage 1 somatic embryos. The embryonal-suspensor mass was induced on a wide range of auxin/cytokinin ratios. However, media containing either 2-mu-M NAA and 10-mu-M BA, or 10-mu-M NAA and 5-mu-M BA produced somatic embryos that gave the highest frequency of plantlets. The level of ABA required in the maturation medium for somatic embryos to mature properly varied with the auxin/cytokinin levels in the induction medium on which the somatic embryos were derived. Inclusion of AgNO3 (10 - 100-mu-M) in the induction medium reduced somatic embryogenesis and embryo conversion.