Somatic Embryogenesis From A Group Of Explant Source Trees In Fraxinus Mandshurica

Somatic embryogenesis is the base of gene engineering and selection of mutation, and the precondition of that the system of choiceness series propagation is applied. Influence of explant source tree to somatic embryogenesis in Manchrian ash(Fraxinus mandshurica), which is the method of estimation the approach of propagation. Manchrian ash is one of the important tree species in Northeast China for timber production and landscape establishment. This paper is about somatic embryogenesis and propagation from cotyledons of immature and mature zygotic embryos in Manchurian ash.It was observed that different optimal hormone combinations was necessary for induction of somatic embryogenesis of various source trees, also, the frequency of somatic embryogenesis are different, such as source tree 3, NAA 2 mg/L and BA 0.5 mg/L, 54%;source tree 1, NAA 1.5 mg/L and BA 0.5 mg/L, 18%;source tree 4, NAA 1 mg/L and BA0.5 mg/L, 16%;source tree 2, NAA 1.5 mg/L and BA 0.5 mg/L, 12%.Cotyledons of Mature zygotic embryos from 37 different source trees were used as explants, then somatic embryogenesis efficiency, MS1/2 was the base medium, combinnated with NAA 5mg/L, BA2mg/L, casein hydrolysate 400 mg/L, 70g/L sucrose , 6g/L agar, the pH was adjusted to 5.8 before put in autoclave. There were difference on somatic embryognesis from cotyledons of Manchurian ash in different sides;somatic embryognesis from cotyledons of different Manchurian ash in one side was different, the highest frequency (15%) and none of somatic embryogenesis were together.Global, heart and torpedo somatic embryo proliferate best on MS1/2+ 0.01 mg/L NAA +200 mg/L casein hydrolysate 70g/L sucrose , 6g/L agar, the PH was adjusted to 5.8 before put in autoclave;cotyledonary somatic embryos can germinate on that medium.In cytological study of somatic embryo development, by the way of paraffin. The cytological investigation on somatic embryogenesis showed that the somatic embryos from zygotic cotyledons originated directly from single epidermis cell. Embryogenic cells were small, almost isodiametric, with dense cytoplast, large nucli and nucleolus. Non-embryogenic callus were composed of larger cells, with irregular figures, arranged compactly or loosely, thin cytoplast, little nucli located at one side.Somatic embryogensis underwent the similar course, passing through proembryo, heart, torpedo and cotyledonary stages and Somatic embryos can germinate into seedlings. Vascular bundle differentiated at heart embryo stage that took on the character " 丫 " at torpedo and cotyledonary stages and did not contact with mother tissues. Obvious bipolarity was detected...