The soybean sucrose binding protein gene family: genomic organization, gene copy number and tissue-specific expression of the SBP2 promoter

Abstract

The sucrose binding protein (SBP) from soybean has been implicated as an important component of the sucrose uptake system. Two SBP genomic clones, gsS641.1 and gsS641.2, which correspond to allelic forms of the GmSBP2/S64 gene, have been isolated and characterized. As a member of the seed storage protein superfamily, it has been shown that the SBP gene structure is similar to vicilin genes with intron/exon boundaries at conserved positions. Fluores cence in situ hybridization (FISH) suggested that the soybean SBP gene family is represented by at least two non-allelic genes corresponding to the previously isolated GmSBP1 and GmSBP2/S64 cDNAs. These two cDNAs share extensive sequence similarity but are located at different loci in the soybean genome. To investigate transcriptional activation of the GmSBP2 gene, 2 kb 5'-flanking sequences of gsS641.1 and gsS641.2 were fused to the beta-glucuronidase (GUS) reporter gene and to the green fluorescent protein (GFP) reporter gene and inde pendently introduced into Nicotiana tabacum by Agrobacterium tumefaciens-mediated transformation. The SBP2 promoter directed expression of both GUS and GFP reporter genes with high specificity to the phloem of leaves, stems and roots. Thus, the overall pattern of SBP-GUS or SBP-GFP expression is consistent with the involvement of SBP in sucrose translocation-dependent physiological processes.

Distinct repressing modules on the distal region of the SBP2 promoter contribute to its vascular tissue-specific expression in different vegetative organs

“…These have extensive sequence similarity but are found at different loci in the soybean genome (Contim et al 2003). A third isolated GmSBP cDNA is 99% identical to the previously isolated GmS64/ GmSBP2 gene and may represent an allelic form (Pirovani et al 2002;Elmer et al 2003).…”

“…Members of the SBP family have also been identified in pea (Castillo et al 2000), faba bean (Heim et al 2001), spinach (Warmbrodt et al 1989(Warmbrodt et al , 1991 and Medicago truncatula (Contim et al 2003). At the amino acid level, SBP is most related to cupin domaincontaining proteins and vicilin-like seed storage proteins (about 35% identity and 50% similarity) from other plant species.…”

“…Furthermore, the VfSBPL promoter-mediated expression of a reporter gene has been shown to be restricted to cotyledons (Heim et al 2001). In contrast, the GmS64/GmSBP2 promoter drives expression of linked reporter genes to the vascular tissue of roots, stems and leaves from tobacco transgenic lines (Contim et al 2003). We have recently shown that the GmSBP2 promoter is functionally organized into a proximal region, with the combinatorial modular configuration of plant promoters, and a distal domain, which restricts gene expression to the vascular tissues in vegetative organs (Waclawovsky et al 2006a).…”

High-level Expression of Basic Fibroblast Growth Factor in Transgenic Soybean Seeds and Characterization of its Biological Activity

“…1. These elements could be required for regulation of tissue-specific, lightresponsive or stress-responsive expression (Contim et al 2003).…”

Two Highly Homologous Promoters of a Squash Aspartic Protease Inhibitor (SQAPI) Multigene Family Exhibit Differential Expression in Transgenic Tobacco Phloem and Trichome Cells

“…First are those that express proteins associated with apoplastic and symplastic sugar transport Gahrtz et al 1994;Truernit and Sauer 1995;Riesmeier et al 1993;Yang and Russell 1990;Graham et al 1997;Shi et al 1994;Hedley et al 2000;Contim et al 2003;Ayre et al 2003;Nakamura et al 2003) and second are those that are associated with the major soluble exudate proteins (Clark et al 1997;Bostwick et al 1992;Xu et al 2001). In addition to plant phloem-expressed genes are pathogen phloemexpressed genes that include bacterial and viral genes (Matsuki et al 1989;Sugaya et al 1989;Schmulling et al 1989;Medberry et al 1992;Wu et al 1999;Matsuda et al 2002;Bhattachariya-Pakrasi et al 1993;Yin et al 1997;Hehn and Rodhe 1998).…”