Several methods for gene transfer into plants have been developed and it hás allowed many ofthe world's importam crop lants to be transformed. Transformation using Agrobacterium hás several advantages over vectorless systems, although its efficiency on transferring DNA is still low for many species. Recentty, a technology called SAAT (Sonication Assisted Agrobacterium-mediated Transformation) hás been described, which involves subjecting lhe plant tissue to brief periods of ultrasound m the presence of Agrobacterium. Scanning and light microscopy revealed tíiat SAAT treatment produces a large number of small and uniform wounding through the tissue allowing the Agrobacterium easy access to internai plant tissues. SAAT improved the transfonnation efficiency in several different plant tissues including immature cotyledons, leaf tissue, suspension cultores, somatic and zygotíc embryos from dijferent species such as soybean, cowpea, white spruce, wheat and maize. This new method allows the increase of transfonnation rates in several species, especially those more recalcitram to Agrobacterium -mediated transfonnation.
Agrobacterium; plant transfonnation; SAAT; sonication