TRANSIENT EXPRESSION OF FOREIGN CHIMERIC GENES IN THE GYMNOSPERM HYBRID LARCH FOLLOWING ELECTROPORATION

A transient gene expression system using electroporation and naked plasmid DNA has been developed for hybrid larch (Larix x eurolepis). The beta-glucuronidase, neomycin phosphotransferase II, and chloramphenicol acetyltransferase genes were used effectively, but the latter was found to be the most useful. Electroporation conditions were comparable with protocols developed for other conifer and angiosperm species. Of the parameters tested the optimum conditions were 300 V, 150-mu-F, and 300-mu-g/mL pCaMVCN DNA. The 35S promoter of cauliflower mosaic virus yielded a stronger level of transient expression than the nopaline synthase promoter, which is consistent with other studies. A construct with the wound-inducible promoter of the potato proteinase IIK gene and the chloramphenicol acetyl transferase reporter coding sequence did not yield to any transient gene expression, even after induction with acetylsalicylic acid and exposure to ultraviolet radiation.