Genetic transformation of Eucalyptus globulus through biolistics: complementary development of procedures for organogenesis from zygotic embryos and stable transformation of corresponding proliferating tissue

Stable transformation of Eucalyptus globulus after biolistic DNA delivery was investigated using zygotic embryos as target material. Conditions for plant regeneration were first investigated. Six-day-old cultured embryos, which had shown to be a good target for DNA transient expression, appeared to be suitable for regeneration. Whole plants were recovered through organogenesis after particle gun bombardment. Transformation experiments were performed with a linear T-DNA fragment harbouring GUS and NPTII genes, using the biological and physical conditions defined for optimum transient expression. After 2 months on a culture medium, neoformed GUS-positive calli were obtained from the 'T-DNA' bombarded embryos. GUS-expressing calli were also recovered after selection with kanamycin following bombardment. The integration of both GUS and NPTII genes into the Eucalyptus genome was confirmed by Southern blot analysis, demonstrating stable transformation of Eucalyptus globulus cells for the first time.