ANALYSIS AND OPTIMIZATION OF DNA DELIVERY INTO WHEAT SCUTELLUM AND TRITORDEUM INFLORESCENCE EXPLANTS BY TISSUE ELECTROPORATION

Wheat scutella and tritordeum inflorescences were transformed by tissu e electroporation with plasmid DNA containing a beta-glucuronidase (GU S) gene (gus A) under the control of the rice actin1 promoter. Factors affecting electroporation efficiency were analysed. Important factors were electroporation voltage and pulse length, the volume of electrop oration buffer, the osmoticum of electroporation buffer and medium, th e osmoticum of pre-electroporation culture medium, and pre-electropora tion incubation time and temperature. Maximum transient gene expressio n was obtained with a single pulse of 550 V/cm from a 960-mu F capacit or, using 200 mu l of electroporation buffer, after 2-3 h culture on m edia with 357 mOsm for wheat scutella or 1 day on media with 222 mOsm for tritordeum inflorescences, and 0.5-1 h pre-electroporation incubat ion with DNA at 24 degrees C. Under these conditions, up to 90% of the explants showed GUS expression, and up to 149 expression signals were recorded per replicate. Electroporated explants showed high rates of survival and retained the ability to regenerate plants via somatic emb ryogenesis.