The Study On Genetic Transformation System And EMS Mutation In Vitro Of Rieger Begonia

Rieger Begonia is a species of the Begonias (Begoniaceae), which is a kind ofperennial plant with beautiful color, changeful flower type, great flowers and longflorescence. It is popularized because of blooming during the Spring Festival in China. Atpresent, all varieties of Rieger Begonia come from foreign countries. But, long-distanttransportations not only do bad for the quality of flowers, but also bring down ornamentalpurposes. At the same time, the long growth cycle, disease resistance and culturaltechnology restricts the production of Rieger Begonia in China. So, it is imperative todevelop new varieties by means of the modern advanced breeding techniques in China forthe Rieger Begonia industry.In this work, experiments with different explants from Rieger Begonia with differentcombinations of hormone concentration were performed to obtain higher frequency ofshoot and root induction. Based on this, a highly-efficient genetic transformation systemand a chemically mutational system of EMS were primarily established, which couldprovide a basis for the improvement of breeding systems to Rieger Begonia varieties. Thegeneral results are following:1,The highly-efficient regenerated system was optimized, which provided a basis forgenetic transformation and chemical mutation in vitro. The optimal medium for shootsis The MS medium with 0.5 mg/L 6-BA,0.05mg/L NAA,0.1 mg/L KT,3% sucrose and0.7% agar. And The optimal medium for roots is the 1/2MS medium contained0.2mg/L IBA,0.15mg/L NAA,3% sucrose and 0.7% agar.2,Sensitivities to antibiotic were studied in this work. 100mg/L kanamycin can inhibit theregeneration of leaf explants in Rieger Begonia, but the semi-lethal dose of theregeneration is 25～50mg/L. At the same time, the concentration of cefotaximeexceeding 250mg/L can restrict shooting and rooting at a certain extent.3,The genetic transformation system in Rieger Begonia was established. In this work,leaf explants were Agrobacterium-mediately transformed with gene cycd₂. The resultsof PCR and southern blot revealed that gene cycd₂ had been integrated into genome ofRieger Begonia in T₀ transformants. 4,Effects of EMS are studied on the regeneration of Pdeger Begonia in vitro. Comparedto different concentrations, times and temperatures, 0.4% EMS(Sh, 20℃) is thehalf-lethal dose of the regeneration for leaf explants, which is the optimumconcentration for mutation.5,The result of mutation on leaf explants in Rieger Begonia indicated that 21 varianceswere detected in the M₁. But, RAPD-PCR analysis got DNA polymorphism segmentsin 12 plants, which proved the variances occurred in genome of Rieger Begonia in the12 plants.6,In this work, we studied the genetic stability of the variances and the separation ofchimera variances, variable explants of the 12 plants were regenerated in vitro. In theT1, mutants were separated from the chimera variances. Moreover, 7 variances areheritable, but 4 additional plants were not found the characteristics of the M₁. Up tonow, the study on genetic stability of one in the 12 plants is still on the way.