Functional dissection of a bean chalcone synthase gene promoter in transgenic tobacco plants reveals sequence motifs essential for floral expression |
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Authors: | Ouriel Faktor Jan M. Kooter Richard A. Dixon Chris J. Lamb |
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Affiliation: | (1) Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, 92037 La Jolla, CA, USA;(2) Plant Biology Division, The Samuel Roberts Noble Foundation, P.O. Box 2180, 73402 Ardmore, OK, USA;(3) Present address: Department of Entomology, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, 76100 Rehovot, Irael;(4) Present address: Department of Genetics, Vrije Universiteit, De Boelelaan 1087, 1081HV Amsterdam, the Netherlands |
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Abstract: | Expression of chalcone synthase (CHS), the first enzyme in the flavonoid branch of the phenylpropanoid biosynthetic pathway in plants, is induced by developmental cues and environmental stimuli. We used plant transformation technology to delineate the functional structure of the French bean CHS15 gene promoter during plant development. In the absence of an efficient transformation procedure for bean, Nicotiana tabacum was used as the model plant. CHS15 promoter activity, evaluated by measurements of -d-glucuronidase (GUS) activity, revealed a tissue-specific pattern of expression similar to that reported for CHS genes in bean. GUS activity was observed in flowers and root tips. Floral expression was confined to the pigmented part of petals and was induced in a transient fashion. Fine mapping of promoter cis-elements was accomplished using a set of promoter mutants generated by unidirectional deletions or by site-directed mutagenesis. Maximal floral and root-specific expression was found to require sequence elements located on both sides of the TATA-box. Two adjacent sequence motifs, the G-box (CACGTG) and H-box (CCTACC(N)7CT) located near the TATA-box, were both essential for floral expression, and were also found to be important for root-specific expression. The CHS15 promoter is regulated by a complex interplay between different cis-elements and their cognate factors. The conservation of both the G-box and H-box in different CHS promoters emphasizes their importance as regulatory motifs. |
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Keywords: | chalcone synthase /content/q688376v21033v5t/xxlarge946.gif" alt=" beta" align=" MIDDLE" BORDER=" 0" >- font-variant:small-caps" >d-glucuronidase (GUS) Phaseolus vulgaris flower development tobacco G-box H-box |
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