Transformation of elite white poplar (Populus alba L.) cv. ' Villafranca' and evaluation of herbicide resistance

Transgenic white poplar plants (Populus alba L.) expressing the nptII gene and the bar gene from Streptomyces hygroscopicus have been produced using Agrobacterium tumefaciens-mediated gene transfer. Eleven kanamycin-resistant plant lines were obtained with a transformation frequency of 7%. Successful genetic transformation was confirmed by Southern and northern analyses. The level of resistance to the commercial preparation of phosphinothricin (Basta; Roussel-Hoechst Agrovet) was evaluated by in vitro and in vivo assays. Using in vitro selective conditions for phosphinothricin, only plantlets from four kanamycin-resistant independent lines remained green and continued to grow and root. After transfer to the growth chamber, all selected transgenic lines were shown to be completely resistant to the herbicide Basta with doses equivalent to 6 l ha^-1 (normal field dosage) and were tolerant at concentration of 12 l ha^-1. This is the first report describing the genetic transformation of a P. alba clonal cultivar of commercial interest with a gene of agronomic value.