DNA DELIVERY INTO EUCALYPTUS-GLOBULUS ZYGOTIC EMBRYOS THROUGH BIOLISTICS - OPTIMIZATION OF THE BIOLOGICAL AND PHYSICAL PARAMETERS OF BOMBARDMENT FOR 2 DIFFERENT PARTICLE GUNS

DNA transfer into zygotic embryos of Eucalyptus globulus by microproje ctile bombardment was studied with two devices : a gunpowder apparatus and a compressed-helium system. Using, as a test, the transient expre ssion of a reporter gene, we optimized the physical and biological con ditions of bombardment. Six-day-old cultured embryos were found to be the best target material, and osmotic treatment increased the expressi on 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 pet embryo with a good distribution over the tissue. In our transient expression experiments, the gunpowder and helium devices exhibited similar efficiencies, reli abilities and reproducibilities.