Incubation For New Anti-virus Races By Genetic Transformation In Cattleya, Cymbidium And Cymbidium Hybridum

As one of important ornamental plants, orchids have an important commercial importance in world flower industry. Taxonomically, Orchidaceae is the largest family of flowering plants among monocotyledons, which occupies wide ranges of ecological habitats and exhibits highly specialized morphological, structural, and physiological characteristics. The inefficient transformation of orchids, however, hampered the investigation of orchid gene function and regulation in vivo. Orchid breeding by traditional sexual hybridization was time-consuming due to the long growth and reproductive cycle of these plants, mean while genetic engineering method offers an effective way to introduce novel characters into orchids.Cymbidium Mosaic Virus (CyMV) and Odontoglossum Ringspot Virus (ORSV) have been reported to cause severe damage to orchid plants. To enhance the resistance of orchids to viral phytopathogens, gene transformation was applied on Cattleya, Cymbidium and Cymbidium hybridum orchid. We transformed orchids with a relatively high efficiency via Agrobacterium-mediated transformation and biolistic bombardment. Rhizome or protocorm-like bodies (PLBs) were used as target explants.A protocol was developed to obtain stable transgenic orchids via Agrobacterium-mediated transformation and biolistic bombardment of protocorm-like bodies (PLBs) and rhizome. Agrobacterium tumefaciens strains LBA4404 were used, with each containing a binary vector PBI121,PBI221 with the NPTâ…¡gene as a selectable marker for kanamycin resistance. Plasmid DNA carrying CyMV gene or ORSV gene and the NPTâ…¡genes. The transformed PLBs or Rhizome were proliferated and selected for kanamycin resistance conferred by the introduced NPTâ…¡gene. Shoot regeneration was then induced from the kanamycin-resistant PLBs, and transgenic plantlets were produced.25mg/L kanamycin is appropriate for selection on Cattleya and Cymbidium hybridum.50mg/L kanamycin is appropriate for selection on Cymbidium.The presence of the introduced gene in the transformed orchid plants was confirmed by PCR analysis and sequencing.