Affecting Factors Of Regeneration Of Abnormal Somatic Embryos Of Fraxinus Mandshurica

Manchrian ash(Fraxinus mandshurica Rupr.) is a valuable hardwood species and also an important timber and ornamental species in Northeast China.During somatic embryogenesis of F. mandshurica,we found that somatic embryogenesis rate was low and the abnormal somatic embryogenesis rate was high,which affected synchronization of somatic embryos and restricted somatic embryos' germination,rooting and the plantlets' transplant.The high frequency of abnormal somatic embryogenesis restricted the somatic embryogenesis rate and whose stability of F. mandshurica.We cultured the immature zygotic embryos cotyledon to induce somatic embryo and studied the influence factors and the mechanism by regulating environment factors such as low-temperature and concentration of sucrose,agar,AgNO₃,PEG 4000,ABA,NAA and 6-BA.Single factor,double factors and mix-uniform experimental design were used to study the influence of environment factors on F.mandshurica somatic embryogenesis,and then found out the best culture condition to reduce the abnormal somatic embryogenesis rate and increase normal somatic embryogenesis rate. The results were as follows:Low-temperature pretreatment time and sucrose concentration affected the numbers of somatic embryos,cotyledon somatic embryos and abnormal somatic embryos significantly,but the concentration of agar,PEG 4000,Ag+,ABA,NAA,and 6-BA affected which not significantly. Normal somatic embryogenesis rate increased when explants were treated by low-temperature pretreatment with 20 days.Abnormal somatic embryo number and somatic embryogenesis rate could not be reduced by changing the concentration of sucrose,agar,AgNO₃,PEG 4000,ABA,NAA and 6-BA significantly. The production of abnormal somatic embryos might related with the heredity background of F. mandshurica.Explants(without low-temperature pretreatment) cultured on differential medium of that MS 1/2+CH 400 mg·L^-1+sucrose 70 g·L^-1+6-BA 0.5 mg·L^-1+ABA 2 mg·L^-1+agar 8 g·L^-1 after 2 W induction culture promoted somatic embryogenesis of F.mandshurica,but the abnormal somatic embryogenesis rate were also high.