DNA delivery into Eucalyptus globulus zygotic embryos through biolistics: optimization of the biological and physical parameters of bombardment for two different particle guns.

DNA transfer into zygotic embryos of Eucalyptus globulus by microprojectile bombardment was studied with two devices: a gunpowder apparatus and a compressed-helium system. Using, as a test, the transient expression of a reporter gene, we optimized the physical and biological conditions of bombardment. Six-day-old cultured embryos were found to be the best target material, and osmotic treatment increased the expression rate. Conditions of bombardment (particle acceleration and quality of the particle: DNA mix) were studied. In optimal conditions, we were able to obtain up to 130 GUS expression events per embryo with a good distribution over the tissue.In our transient expression experiments, the gunpowder and helium devices exhibited similar efficiencies, reliabilities and reproducibilities.