5′ Analysis of the soybean leghaemoglobin lbc ₃ gene: regulatory elements required for promoter activity and organ specificity

Abstract

The soybean leghaemoglobin lbc3 gene promoter was analysed in transgenic Lotus corniculatus plants. Hybrid‐promoter constructions and 5′ deletions were studied using chimeric genes composed of the various promoters, the chloramphenicol acetyltransferase (CAT) coding sequence and the lbc3 3′ flanking region. A 5′ Bal31 deletion series mapped a strong positive regulatory element between −1100 and −950. A weaker element located between −230 and −170 defined the minimum 5′ region required for detectable promoter activity. Reactivation of inactive promoters with deletion endpoints between −230 and the transcription initiation site was obtained employing the constitutive cauliflower mosaic virus (CaMV) 35S enhancer. The position of cis regulatory element(s) required for nodule‐specific expression was defined to 37 bp between −139 and −102. This region contains sequences conserved in other leghaemoglobin and nodulin genes. No indispensable control elements were found on the lbc3 3′ flanking region.

The Sym35 Gene Required for Root Nodule Development in Pea Is an Ortholog of Nin from Lotus japonicus

“…However, the sequence content of two adjacent 14-and 12-nucleotide blocks located between position Ϫ384 and Ϫ352 of the LjNin promoter and between Ϫ385 and Ϫ352 of the PsNin promoter attracts attention. The proximal 14-nucleotide-long conserved sequence is a perfect match to the 3Ј half (TTGTCTCTT) of the extended organ-specific element (AAAGATNNTT-GTCTCTT) first identified in the soybean and Sesbania rostrata leghemoglobin promoters and subsequently found in other nodule expressed genes (Stougaard et al, 1987;Ramlov et al, 1993;Szczyglowski et al, 1994). Interestingly, the same sequence encompasses a TGTCTC sequence shown in Arabidopsis to be an auxin-responsive element binding the ARF1 transcription factor (Ulmasov et al, 1997).…”

Transcriptional snapshots provide insights into the molecular basis of arbuscular mycorrhiza in the model legume Medicago truncatula

“…1; Fehlberg et al 2005). Thus, although detailed promoter studies in AM roots are obviously far from comprehensive, it emerges that the situation is more complex than in the root nodule symbiosis where organspecific-elements (OSEs) were reported to be sufficient to direct gene expression to the infected cells of root nodules (Stougaard et al 1987).…”

Site-specific mutagenesis of the nodule-infected cell expression (NICE) element and the AT-rich element ATRE-BS2* of the Sesbania rostrata leghemoglobin glb3 promoter.

“…A less conserved AAAGAT-like motif was identified at an analogous position in the promoter region of Ib genes from M. A comparison of the DNA sequences in the 5' upstream regions of (1eg)hemoglobin genes from S. rostrata (Metz et al, 1988). soybean (lba, lbcl, lbc2, and lbc3; Stougaard et al, 1987), pea (pslb; Nap, 1988), M. truncatula (Mtlbl and MtlbP;Gallusci et al, 1991), M. sativa (Msl and Msplb2;Davidowitz et al, 1991), T: tomentosa (Tmma; Bogusz et ai., 1990), and I ? andersonii(far8; Bogusz et al, 1990) is shown.…”

“…In the equivalent region of the soybean lbc3 promoter, two important elements have been identified: an OSE (-139 to -102) relative to the start point of transcription, which is required but not sufficient for nodule-specific expression, and an NE (-102 to -49), which is apparently involved in repression of lbc3 promoter activity (Stougaard et al, 1987(Stougaard et al, ,1990. Together, OSE and NE were found to be able to confer a nodule-specific (enhanced) pattern of gene expression on the CaMV 35s promoter in transgenic L. corniculatus plants (Lauridsen et al, 1991).…”

“…The promoter regions of the Ibc3 gene from soybean and the gIb3 gene from the stem-nodulated tropical legume Sesbania rosfrafa (see de Bruijn, 1989) have been studied in the most detail. 60th soybean and Sesbania Ib 5' upstream regions have been shown to confer nodule-specific expression on reporter genes in indeterminate nodules formed on transgenic alfalfa (de Bruijn et al, 1989(de Bruijn et al, ,1990) and determinate nodules induced on Lofus corniculafus plants (Stougaard et al, 1986(Stougaard et al, , 1987(Stougaard et al, , 1990Szabados et al, 1990). Ib promoter activity has been shown to be confined to the infected zone of the nodules induced on transgenic Lofus plants and appeared to be most predominant in the infected cells (Szabados et al, 1990;Lauridsen et al, 1 993).…”