High Frequency Induction And Germination Promotion For Somatic Embryos Of Sorbus Pohuashanensis

Sorbus pohuashanesis Hedl.is an important ornamental tree species in north China, Somatic embryogenesis and plant regeneration plays an important role in establishing fast propagation systems for improved materials with special traits.High efficiency induction and germination promotion of somatic embryos of Sorbus pohuashanesis were studied here.The somatic embryo induction process were observed simultaneously by useing scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results are as follows:(1) Somatic embryogenesis of S.pohuashanesis on cotyledon explants treated by 1 mol·L^-1 mannito pretreatment the for 24 hours was improved evidently,and the Somatic embryos regenerated directlyfrom surface cell of the explants.SEM and TEM observation revealed that epidermal cell lineage of cotyledon explants pretreatmented with mannitol turned rapidly to irregular,cell wall became more thick and cell division planes was random.This indicates that pretreatment might strongly disturb the cell-to-cell relationship and produced a favorable status for somatic embryogenesis.(2) MS + 0.01mg·L^-1 rhodofix and incubated 30 somatic embryo explants per dish under illumination was most favorable to proliferation of secondary somatic embryogenesis,the proliferation rate could be reached high-level.Cultured in dark was propitious to somatic embryo maturation,on the optimum medium of MS + 200 mg·L^-1 CH + 5%sucrose + 5 g·L^-1 PEG6000,the maturation rate could be achieve to 59%.Appearance of mature somatic embryos would be described as cotyledons thick,milkly or pale yellow and about 4-5 mm long in diameter.(3) After maturation cultured for 35 days,the somatic embryos germinated well on MS+ auxin + 0.1%active carbon,germination rate could be reached 50%.The above results showed that effective mannitol pretreatment can promote high efficiency induction of somatic embryos of Sorbus pohuashanensis and the basic conditions for proliferation and maturation of the somatic embryos can be controled artificially.