Both internal and external regulatory elements control expression of the pea Fed-1 gene in transgenic tobacco seedlings.

Abstract

In previous studies using leaves of light-grown transgenic tobacco plants, we have shown that sequences located within the transcribed region of the pea Fed-l gene (encoding ferredoxin I) are major cis-acting determinants of light-regulated mRNA accumulation. However, we show here that these internal sequences are less important for the Fed-l light response in etiolated tobacco seedlings than they are in green leaves and that upstream elements confer organ specificity and contribute significantly to Fed-7 light responses in etiolated material. Light effects mediated by upstream response elements are thus most pronounced during the initial induction of gene activity, whereas internal elements play a more prominent role in modulating Fed-l expression once the gene is already active.

Light-regulated expression of the Arabidopsis thaliana ferredoxin gene requires sequences upstream and downstream of the transcription initiation site

“…Recently, Dickey et al [ 15 ] identified a light-regulatory element in the 5' portion of the pea ferredoxin transcript, capable of conferring light responsiveness to three different reporter genes. These results suggest that post-transcriptional processes contribute predominantly to the expression of the pea ferredoxin gene in mature plants, whereas transcriptional processes play a more prominent role in seedlings [ 13].…”

“…In addition, results of Dickey et al [15], obtained with the pea ferredoxin gene in transgenic tobacco plants, suggest that post-transcriptional processes play a dominant role in the expression of this gene in mature plants, whereas transcriptional processes are more prominent in seedlings [ 13]. We decided to investigate the light regulation of the A. thaliana ferredoxin gene in mature tobacco plants by searching for cisregulatory elements in this gene.…”

“…Light-treated tobacco seedlings transformed with a pea ferredoxin promoter-GUS fusion (FD-GUS) produced three-to four fold more GUS m R N A than the dark controls, whereas a chimeric construct of the constitutive cauliflower mosaic virus 35S promoter fused to the transcribed region of the pea ferredoxin gene (35S-FD) showed a two fold increase in fed-1 m R N A levels in light-treated tobacco seedlings. This indicates that, besides transcriptional, also post-transcriptional processes play a role in the regulation of the pea ferredoxin gene in tobacco seedlings [13]. In mature transgenic tobacco plants, however, the involvement of post-transcriptional regulation for the pea gene was much more pronounced: 35S-FD m R N A levels were four-to six fold higher in leaves of light-treated plants than in dark controls, whereas the FD-GUS fusion displayed a constitutive activity in these plants [ 14].…”

Developmental, circadian and light regulation of wheat ferredoxin gene expression

“…Evidence for this has been obtained from studies with transgenic tobacco plants containing chimeric constructs of 5'-and 3'-flanking regions of the pea ferredoxin gene attached to a fi-glucuronidase reporter gene [9]. Both upstream promoter elements and regions of transcribed sequence were shown to be involved in lightregulated gene expression, although there were differences in their relative contributions in greening seedlings and green leaves [13,14]. The 5'-untranslated region of the pea ferredoxin gene was able to confer light responsiveness on reporter genes in transgenic tobacco [7], although no evidence for light-regulatory elements in a similar region of the Arabidopsis gene was found when expressed in transgenic Arabidopsis plants [4].…”

Transgenic analysis of the 5?- and 3?-flanking regions of the NADH-dependent hydroxypyruvate reductase gene from Cucumis sativus L.

“…4). This pattern has also been observed at the transcript level for both the -90 35S/GUS fusion [20] and the full-length 35S/GUS fusion [ 16] as well as at the level of GUS activity for the 35S/GUS fusion [47].…”