Studies On The Induction Of Somatic Embryos & Physiological And Proteomic Changes During Somatic Embryogenesis In Cassava

Cassava(Manihot esculenta Crantz) belonging to Euphorbiaceae family is one of the most important energy producing crops in its root tuber, and distributes in southeast、tropic Africa and Central America. Cassava somatic embryogenesis is one of the important pathways in vitro plant regeneration and gene transformation.In this thesis, four cassava cultivars (SC5, SC6, SC7 and SC8) were used for the following researches:1. Establishment of cassava in vitro culture system.2. Effects of explants, genotype and CaCl2 on somatic embryogenesis.3. Establishment of cassava somatic embryogenesis system.4. Preliminary studies on the physiological and biochemical changes during the somatic embryogenesis.5. Preliminary research on the differentially expressed proteins by 2-DE. It would provide effective in vitro culture system for the rapid reproduction and genetic engineering research; and understand of the physiological and proteomic changes during somatic embryogenesis in Cassava. The main results are as follow:1. The cassava renewable system was successfully established through organogenesis and utilization the stem segments. The system had high efficiency, stable regeneration capacity, and higher genetic stability.2. The tip buds were regarded as the most effective explants for embryonic induction, followed by axillary buds and the cotyledons embryos; while the older leaves of cassava couldn’t induce somatic embryos.3. The effects of CaCl2 on the induction of the cassava primary and secondary somatic embryos were not obvious, but it could maintain and extend the activity of the mature embryos.4. There were close relationship between embryogenic capability and anti-oxidase activity.The activities of SOD, POD and CAT were related to embryogenic cell differentiation and early embryonic development of cassava. Ca2+ had some influence on the anti-oxidase activity during the development of somatic embryos.5. The isozyme activity was variety during the development of somatic embryos.6. There were close relationship between embryogenic capability and the content of soluble protein. Ca2+ had some influence on the content of soluble protein during the development of somatic embryos.7. The differentially expressed proteins between non-embryogenic calli and mature embryos of cassava were analyzed by 2-DE. There were five areas in the gel showed obviously different through the analysis of Imagemaster 2-DE. Furthemore,39 differentially expressed proteins had been analyzed from these areas, among which 6 of them were up- and down-regulated lesser than 2-folds; 22 of them were up-and down-regulated more than 2-folds, and 6 of them were new proteins.