Somatic embryogenesis and plant regeneration in yakutanegoyou, Pinus armandii Franch. var. amamiana (Koidz.) Hatusima, an endemic and endangered species in Japan

Abstract

Induction of somatic embryogenesis in Pinus armandii var. amamiana, an endemic and endangered species in Japan, was initiated from megagametophytes containing immature zygotic embryos on both media with and without plant growth regulators. Across nine open-pollinated families initiation frequency ranged from 0 to 20%, with an average of 1.5%. Embryogenic cultures were maintained and proliferated on a medium supplemented with 2,4-dichlorophenoxyacetic acid (3 μM) and 6-benzylaminopurine (1 μM). Maturation of somatic embryos occurred on medium containing maltose (50 g l−1), activated charcoal (2 g l−1), abscisic acid (100 μM), and polyethylene glycol (100 g l−1). The frequencies of germination and plant conversion of somatic embryos differed among the embryogenic lines from 16 to 51% and from 12 to 40%, respectively. Growth of regenerated somatic plants has been monitored in the field.