In Vitro Germination Using Hybrid Seeds And RAPD Analysis From Cymbidium Longibracteatum And C.hybridium

Studies were carried out on distant hybridization and hybrid seed generation in vitro using Cymbidium longibracteatum'cuixian', C. Moring Moon'Great Tiger', C. hybridium Enzan Stream'Orpheus' as material. The progenies and their parents were analysed by RAPD markers. The objective of the studies was to creat new germplasm by distant cross. The main results are as follows.1.Hybrid fruit could be obtained using Cymbidium longibracteatum as the female parent, C.hybridium as the male parent, in which Cymbidium longibracteatum'cuixian'×C. hybridium Enzan Stream'Orpheus'resulted in the highest rate of 78.5%, while no hybrid fruit could be obtained using C. hybridium as the female parent, Cymbidium longibracteatum as the male parent. Using Cymbidium longibracteatum as parents, the success rate was 100%.2. The optimal medium for seed germination in vitro was MS+NAA0.1mg/L+6-BA0.5mg/L+Tryptone50mg/L+AC1000mg/L. The best medium for PLB multiplication was MS+NAA0.5mg/L+6-BA0.5mg/L+KT0.05mg/L, on which the proliferation rate was 6.07. PLB size of 3.0cm in diameter was the most advantageous to proliferation. Yeast extract at 150mg/L added to the medium was in favar of the propagation of PLBs. The best medium for shoot differentiation was MS+NAA0.1mg/L+6-BA2.0mg/L+Tryptone250mg/L+AC1.0g/L with the shoot differentiation rate being over 88.33%. The medium MS+NAA0.2mg/L+Tryptone250 mg/L+TDZ1.0mg/L was fit for proliferation of cluster buds, in which proliferation rate was 5.38. The best medium for root formation and growth was MS+AC1.0g/Land MS+NAA0.1mg/L+AC1.0g/L, in which the rooting rate reached 100%, average root length was 2.4-2.54cm. The medium for obtaining the largest number of roots was MS+NAA0.1mg/L+AC0.5g/L, giving rise to an average root number of 2.06. The transplanting survival rate of the seedlings was 93.02%.3.21 random primers screened from 100 primers were used for PCR. Among a total of 180 DNA bands observed,164 (91.11%) were polymorphic.The average number of DNA bands and polymorphic DNA bands amplified by each primer were 8.57 and 7.81, respectively. Genetic similarities among individuals based on dice coefficients ranged from 0.7222～0.7722. The dendrogram showing the genetic relationships among individuals was constructed using UPGMA cluster analysis. The genetic similarity of hybrids was somewhat closer to C. hybridium Enzan Stream'Orpheus'(X).