Physiological And Biochemical Characteristics Of Different Development Stages Of Somatic Embryo Of Picea Mongolica

Picea mongolica is a rare and precious species,and it is a unique new species in China.Because of natural and human factors,the resources of P.mongolica are becoming less and less,and the ecosystem is seriously damaged.The use of embryogenic callus can effectively protect the germplasm resources of P.mongolica.Somatic embryogenesis is the expression of plant cell totipotency and a new way of rapid propagation.The mechanism,regulation and maintenance of somatic embryogenic callus are important research topics for somatic embryogenesis.Mature embryos are used as explants to induce embryogenic callus and somatic embryogenesis of P.mongolica at different developmental stages,the mechanism of somatic embryogenesis of P.mongolica was studied from morphology,tissue cytology,soluble protein content,soluble sugar content,soluble starch content,POD activity,SOD activity and CAT activity.The research results are as follows:(1)According to the developmental process and morphological characteristics of somatic embryos of P.mongolica,they are divided into:when the differentiation is 5-15 d,it is the development stage of globular embryos.When the differentiation is 15-25 d,it is the development stage of heart-shaped embryos.When the differentiation is 25-35 d,it is the early development stage of cotyledon embryos.After 35 d of differentiation,it enters the maturity stage of cotyledon embryos,35 of which it is the mid-embryo embryo in 35-45 d,and the late cotyledon in 45-55 d.(2)The histological structure of somatic embryos of P.mongolica showed that embryogenic callus was composed of embryogenic cells and embryogenic cell clusters produced by division.Embryonic cell masses have larger nuclei and thicker cytoplasm.Somatic embryo development through the four stages of the original embryo,globular embryo,heart-shaped embryo and cotyledon embryo,consistent with the morphological observation.(3)The change of soluble protein content during somatic embryogenesis of P.mongolica reflects the physiological,biochemical and metabolic specificity of somatic embryogenesis at different developmental stages,which is closely related to the physiological state of somatic embryogenesis at different developmental stages,and provides material and energy basis for the differentiation of embryonic cells and the development and germination of somatic embryos.(4)The changes of soluble sugar and soluble starch content are closely related to the differentiation ability of embryogenic cells,and also reflect the physiological activities of somatic embryos in different developmental stages,providing a material and energy basis for the differentiation and development of somatic embryos and play an important role in promoting.(5)In the process of somatic embryos of P.mongolica,POD,SOD,CAT and other three enzymes act synergistically to decompose H2O2 produced by somatic oxygen metabolism,so that the production and elimination of reactive oxygen species in embryonic cells achieve equilibrium and regulate and promote the differentiation and development of somatic embryos.