TRANSIENT AND STABLE TRANSFORMATION OF WHEAT WITH DNA PREPARATIONS DELIVERED BY A BIOLISTIC METHOD

An optimized procedure for transformation of wheat with the use of a B iolistic Particle Delivery System PDS 1000/He to deliver foreign DNA i s described in detail. The bacterial uidA and bar genes (both driven b y plant promoters) were utilized as the reporter and selectable marker genes, respectively. Moderately high gas pressure appeared to be most important to achieve the highest level of transient GUS expression in target tissues. There was, however, no apparent correlation between t ransient and stable GUS expression. The presence of telomeric DNA sequ ences in an uidA gene-containing vector did not influence transient GU S expression but, apparently, prevented its stable expression. Mechani cal lesions caused by the bombardment (tungsten particles) seemed to b e less severe when embryo-derived calli, instead of freshly excised im mature embryos, were used as the target tissue. The limited ability of callus cells for regeneration, together with a restricted number of c ells that receive the foreign DNA by particle bombardment, result in a low efficiency of wheat stable transformation.