Conifer genetic engineering: transgenic Pinus radiata (D. Don) and Picea abies (Karst) plants are resistant to the herbicide Buster

A biolistic transformation procedure was applied to co-transform embryogeni c tissue of Pinus radiata and Picea abies with two plasmid DNAs. The first vector contained the bar gene, specifying resistance to the herbicide glufo sinate, under the control of the maize ubiquitin promoter. This plasmid als o contained the Pinus radiata germin cDNA sequence, in either sense or anti sense orientation, driven by the ubiquitin promoter. The second vector cont ained both the nptII gene under control of the CaMV 35S promoter for select ion of transgenic tissue on geneticin and the uidA reporter gene under cont rol of the double CaMV 35 promoter. Polymerase chain reaction analysis of s elected geneticin-resistant tissue showed that the transformation rates for the co-bombarded plasmid were high in both Pinus radiata (75%) and Picea a bies (86%). A combination of phenotypic analysis and Northern hybridisation demonstrated that a number of the transgenic lines expressed all four tran sgenes. Regenerated plantlets from Pinus radiata and Picea abies transgenic lines were spray-tested with commercial rates of Buster (glufosinate at 0. 5, 1.0, 2.0 and 3.0 kg active ingredient per hectare). Transgenic plants su rvived and continued to grow with minor or no damage to their needles, wher eas non-transgenic plants regenerated from the same cell lines died within 8 weeks of spraying. To our knowledge, this is the first report on genetica lly engineered herbicide resistance in conifers, and the results demonstrat e that this trait is a feasible option for plantation forestry.