Ri-plasmid mediated transformation and regeneration of Ulmus procera (English Elm)

Infection of Ulmus procera (English elm) clone SR4 internodal stem explants with Agrobacterium tumefaciens C58 c1 pRiA4b resulted in callus developmen t and extensive hairy root production. Shoots which regenerated from hairy roots, following an extended culture period, were dwarf in stature, with re duced apical dominance and wrinkled leaves when compared with wild type U. procera SR4. Shoots were rooted successfully and plants with extensive root systems have been transferred to soil. The transgenic status of regenerant s was confirmed by PCR analysis and DNA sequencing of pRiA4b TL- and TR- DN A rolA (329 bp) and agropine synthase (490 bp) primed amplimers, which were 100% homologous to the expected sequences. No vir D1 primed PCR products w ere obtained, indicating that the Agrobacterium was successfully removed. T he potential of Ri plasmid mediated transformation for inducing altered elm xylem structure, restricted spread of the Dutch elm disease fungus and in phytoremediation is discussed.