THE PROMOTER OF BARLEY TRYPSIN-INHIBITOR BTI-CME, DISCRIMINATES BETWEEN WHEAT AND BARLEY ENDOSPERM PROTOPLASTS IN TRANSIENT EXPRESSION ASSAYS

Several promoter fragments from the barley gene coding for trypsin inh ibitor, BTI-CMe, have been fused to the beta-glucuronidase (GUS) repor ter gene and these chimeric constructs used for transient expression i n protoplasts. Transfection of developing endosperm protoplasts from b arley (cv Bomi) show a maximum GUS expression of about 50% of that dri ven by the cauliflower mosaic virus 35S promoter, while in wheat endos perm protoplasts expression is less than 10%. No significant expressio n is found in transfected leaf protoplasts from barley, wheat or tobac co (<2% of the 35S control). All the information required for endosper m and barley specificity is present in the 343 bp proximal to the tran slation initiation site.