Induction, development and maturation of somatic embryos in Bunge's pine (Pinus bungeana Zucc. ex Endl.)

Embryogenic tissue was induced from developing immature zygotic embryos in Bunge's pine (Pinus bungeana Zucc. ex Endl.). Induction rate reached 84.4% with our best treatment. Zygotic embryos were dissected from megagametophytes and inoculated on different induction media, DCR1 (Gupta PK, Durzan DJ (1985) Plant Cell Rep 4:177-179), BM1 (Gupta PK, Pullman G (1991) U.S. Patent No. 5,036,00) and MSG (Becwar MR, et al. (1988) Somatic cell genetic of woody plants. Kluwer Academic Publishers, Dordrecht, pp. 1-18), supplemented with 2,4-dichlorophenoxyacetic acid (2, 4-D) and 6-benzylaminopurine (BA). DCR1 was the best medium for initiating embryogenic tissue. Induction rates were affected significantly by developmental stages of explants. The highest induction rate was obtained with embryos collected on either June 20 or June 30 with 10 mg 1(-1) 2, 4-D and 4 mg 1(-1) BA. Embryogenic tissue was subcultured monthly on DCR1 medium supplemented with 0.3 mg 1(-1) 2, 4-D and 0.2 mg 1(-1) a-naphthaleneacetic acid. In order to enhance embryo maturation, embryogenic tissue was transferred onto DCR1 medium for two weeks, in which 1,000 mg 1(-1) myo-inositol was included and all plant growth regulators were eliminated. This pretreated tissue was then transferred onto a maturation medium that was DCR1 medium containing 50 g 1(-1) sucrose and 0.1 mg 1(-1) indolebutyric acid. In this study, benefits of embryo maturation were not observed when abscisic acid and polyethylene glycol were applied in the culture.