Evaluation of different promoters driving the GFP reporter gene and selected target tissues for particle bombardment of Dendrobium Sonia 17

Three different morphological callus types, identified as type A, B and C, and tips of in vitro inflorescences were used as target tissues for genetic transformation. Five different DNA plasmids carrying a synthetic green fluorescent protein (gfp) gene driven by different promoters, CaMV 35S, HBT, and Ubi1 were tested for the genetic transformation of Dendrobium Sonia 17. 35S-sgfp-TYG-nos (p35S) with the CaMV 35S promoter showed the highest GFP transient expression rate, while the HBT and Ubi1 promoters showed a relatively lower expression rate in all of the target tissues tested. The highest number of GFP-expressing cells was observed on day 2 post-bombardment, and the number declined gradually over the course of the next 2 weeks. Type A and B callus were found to be the best potential target tissues for genetic transformation.