Induction of somatic embryogenesis in Pinus roxburghii Sarg.

Embryogenic calli were initiated from embryonic explants of Pinus roxburghi i using female gametophytes containing immature pre-cotyledonary embryos. Z ygotic embryos were collected at different developmental stages and culture d on various media. Initiation of embryogenic calli was achieved in pre-cot yledonary zygotic embryos of a 0.1-mm to 1.2-mm embryonal head on Douglus f ir cotyledon revised medium (DCR) medium supplemented with 2,4-D or NAA and BA. Embryogenic callus development was initiated from the suspensor region of immature embryos. The method of immature embryo culture was significant as rapid embryogenic callus development occurred in megagametophytes where the suspensor was stretched onto the medium from the cut micropylar end. S ixty embryogenic lines were established from 2500 explants cultured during one season. A pro-embryo with six to eight meristematic cells and suspensor of six to ten long, vacuolated cells dominated the early phase of the call us development. Cleavage polyembryony occurred in proliferating callus, con stituting a method of multiplication of these somatic embryos. Somatic embr yos developed to stage-I and stage-II embryos on DCR medium supplemented wi th 5 mu M 2,4-D or 10 mu M NAA.