5' Analysis of the soybean leghaemoglobin lbc3 gene: regulatory elements required for promoter activity and organ specificity

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RESUMO

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.

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