Somatic Embryogenesis in Japanese Black Pine (Pinus thunbergii Parl.)

Abstract

Somatic embryogenesis in Japanese black pine (Pinus thunbergii Parl.) was initiated from megagametophytes containing immature zygotic embryos. Embryogenic cultures were maintained and proliferated in a medium supplemented with 3 μM 2,4-dichlorophenoxyacetic acid, 1 μM 6-benzylaminopurine, 30 g l−1 sucrose, and 1.5 g l−1 l-glutamine. The somatic embryo maturation experiments were performed in darkness at 25 °C. Embryogenic tissues were cultured on maturation media containing 50 g l−1 maltose, 2 g l−1 activated charcoal, 100 μM abscisic acid, and 100 g l−1 polyethylene glycol. Desiccation of somatic embryos at high relative humidity resulted not only in a marked increment in germination frequency but also subsequently improved plant conversion rate. In addition, this treatment resulted in a considerable improvement of synchronization of the germination period, compared to those of untreated control. Somatic plants were acclimatized and their growth has been monitored in the field.