A Preliminary Study on Open Tissue Culture and Genetic Stability of Rhododendron Plantlets

  Objective  An open tissue culture with added bacteriostatic agents in medium for disinfection and disease prevention was established and genetic stability of the plantlets verified for the development of commercialized propagation of rhododendron.

  Method  Terminal buds and stem segments with attached axillary buds were cut from current year branches of Rhododendron pulchrum Sweet plants. Methods using bacteriostatic agents in varied concentrations to disinfect the cut tissues and prevent infection during proliferation stages in an open tissue culture were evaluated. Genetic of the materials in transition from parent to plantlet was scrutinized using an ISSR molecular marker technology to ensure a reliable stability in the process.

  Result  The explants could be adequately disinfected with 10% H₂O₂ for 10 to 15m. A survival rate of terminal buds at 61.67% with a contamination rate of 33.33% and that of stem segments at 23.33% with a contamination rate of 68.33% were achieved. For the open tissue culture, 0.01% addition of NaClO in the medium was found sufficient to achieve the bacteriostatic effect with a survival rate of 62.22% on the plantlets, which had abundant, slender, new leaves and a proliferation coefficient of 3.067. The ISSR molecular maker analysis showed high genetic similarity coefficients ranging from 0.919 to 0.995 between the disinfected explants, the test-tube buds, and the exophyte plantlets.

  Conclusion  This study preliminarily explored the open tissue culture for the feasibility of rhododedron tissue factory nursery. The cut rhododendron tissues for the culture was satisfactorily disinfected with 10% H₂O₂ in 10-15 m. The survival rate of terminal buds after the treatment was higher than that of stem segments. In the early stage of the open tissue culture, a 0.01% addition of NaClO in medium provided sufficient bacteriostatic effect without significant reduction on the survival rate and proliferation coefficient of the treated plantlets. The genetic distance between the parent and the explants remained close, indicating little variation introduced by the propagating operation. The disinfection method and culture procedure appeared feasible for the development of rhododendron seedling generation at nurseries.