A COMPARISON OF THE ACTIVITY OF 3 CAULIFLOWER MOSAIC-VIRUS 35S PROMOTERS IN RICE SEEDLINGS AND TOBACCO (BY-2) PROTOPLASTS BY ANALYSIS OF GUS REPORTER GENE TRANSIENT EXPRESSION
Kt. Pih et al., A COMPARISON OF THE ACTIVITY OF 3 CAULIFLOWER MOSAIC-VIRUS 35S PROMOTERS IN RICE SEEDLINGS AND TOBACCO (BY-2) PROTOPLASTS BY ANALYSIS OF GUS REPORTER GENE TRANSIENT EXPRESSION, PLANT SCI, 114(2), 1996, pp. 141-148
The cauliflower mosaic virus (CaMV) 35S promoter is active in most pla
nt species and has been used for genetic engineering to obtain strong,
constitutive expression of numerous, unrelated genes. We examined the
transient expression of constructs in which the uidA (GUS) reporter g
ene was driven by three somewhat different, independently isolated CaM
V 35S promoters. These CaMV 35S promoters differed principally in 5-6
bases outside the region containing cis-acting regulatory elements, bu
t they were identical in sequences within known regulatory elements. P
lasmid DNA containing the chimeric constructs was delivered to protopl
asts derived from cultured BY-2 tobacco cells by electroporation and t
o rice embryos by DNA uptake during imbibition. GUS enzyme activity wa
s determined by a fluorometric method 72 h after protoplast electropor
ation. The rice embryos were germinated after DNA uptake during imbibi
tion and GUS activity was determined histochemically and fluorometrica
lly in 7-day-old seedlings. All three CaMV 35S promoters gave similar
levels of GUS expression in rice seedlings, both in terms of the patte
rn of expression in the various seedling tissues and in terms of the t
otal level of GUS activity per seedling. In contrast, there was nearly
a 14-fold difference in the activity of the promoters in the tobacco
protoplasts. Promoter activity in tobacco appeared to be strongly affe
cted by the sequence near the transcriptional start site where the pro
moters differed. These results suggest that monocots and dicots may ut
ilize somewhat different signals for transcription initiation.