Regulation of beta-glucuronidase expression in transgenic tobacco plants by an A/T-rich, cis-acting sequence found upstream of a French bean beta-phaseolin gene.

Abstract

A 0.8-kilobase fragment from the 5'-flanking region of a French bean beta-phaseolin gene yielded strong, temporally regulated, and embryo-specific expression of beta-glucuronidase (GUS) in transgenic tobacco plants, paralleling that found for the seed protein phaseolin [Sengupta-Gopalan, C., Reichert, N.A., Barker, R.F., Hall. T.C., and Kemp, J.D. (1985) Proc. Natl. Acad. Sci. USA 82, 3320-3324]. Gel retardation and footprinting assays using nuclear extracts from immature bean cotyledons revealed strong binding of nuclear proteins to an upstream region (-628 to -682) that contains two inverted A/T-rich motifs. Fusion of a 103-base pair fragment or a 55-base pair synthetic oligonucleotide containing these motifs to a minimal 35S promoter/GUS cassette yielded strong GUS expression in several tissues. A different pattern of GUS expression was obtained in immature embryos and germinating seedlings from the nominally constitutive, full-length, 35S promoter. Whereas GUS expression under the control of the 0.8-kilobase beta-phaseolin regulatory region is limited to immature embryos, expression from constructs containing the A/T-rich motifs is strongest in roots. These data, combined with S1 mapping, provide direct evidence that a plant upstream A/T-rich sequence that binds nuclear proteins can activate transcription in vivo. They also indicate that additional regulatory elements in the beta-phaseolin 5'-flanking region are required for embryo-specific gene expression.

The novel gene CpEdi-9 from the resurrection plant C. plantagineum encodes a hydrophilic protein and is expressed in mature seeds as well as in response to dehydration in leaf phloem tissues

“…Further, one Myb and two Myb-like recognition sites, and one sequence which closely resembles an ABA-inducible Sph-containing element or Sph box (ASCE), which is conserved in many seedspecific promoters (Hattori et al 1992), were identified (Table 1). Two regions rich in A/T are located between À539 and À424 bp, and they may act as general enhancers of gene expression (Bustos et al 1989). We also identified the sequence of the PB core motif, which is present in promoters of pollen-specific genes of tomato (Twell et al 1991).…”

“…Data are shown as the mean of at least three independent measurements and error bars indicate the SE the naturally desiccation-tolerant tissues pollen and seeds (specifically embryos; Cuming 1999; Bartels 1999), which supports a role for these proteins in desiccation. Previous studies of seed-specific genes have shown that A/T-rich sequences in the promoter can act as general enhancers of seed specific expression (Bustos et al 1989). Such sequences are present in the CpEdi-9 promoter and could promote expression in seeds.…”

Cis-regulatory elements used to control gene expression in plants

“…β-phaseolin promoter from bean is another promoter of described activity (Bustos et al 1989). β-1,3-glucanase promoter from peas (PsGNS2) is an interesting example of seed-specific construct, as it provides transgene expression in the seed coat.…”

Combinatorial Networks Regulating Seed Development and Seed Filling

“…Phaseolin is the major SSP of bean. Phaseolin (phas) gene expression is temporally and spatially regulated and is completely inactive during the vegetative phase of plant development (Bustos et al, 1989;van Der Geest et al, 1995). Silencing of the phas gene in vegetative tissues was associated with the presence of a nucleosome positioned over the three phased TATA boxes present in the phas promoter (Kadosh & Struhl, 1998).…”