, Volume 199, Issue 4, pp 515-519

Disruption of an overlapping E-box/ABRE motif abolished high transcription of the napA storage-protein promoter in transgenic Brassica napus seeds

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Abstract

The storage protein napin is one of the major protein components of Brassica napus L. (oilseed rape) seeds. To investigate the transcriptional regulation of the napin promoter, different constructs of the napin gene napA promoter were fused to the Escherichia coli uidA gene and transformed into B. napus. A -152-bp promoter construct directed a strong expression of the marker gene in mature seeds. The 5′ deletion of an additional 8 completely abolished this activity. This deletion disrupted sequence motifs that are similar to an E-box, (CA↓ NNTG) and an ABRE (CGCCA↓CGTGTCC) element (identity is indicated by bold face). Further, internal deletion of a segment corresponding to -133 to -121 caused an eightfold reduction in the activity of the -152 construct. This region contains an element, CAAACAC, conserved in many storage-protein gene promoters. These results imply that the E-box/ABRE-like sequence is a major motif of the napA promoter and suggest that the CAAACAC sequence is important for high activity of the napA promoter. Similar results have been obtained by analysing some of the constructs in transgenic tobacco, suggesting that many of the cis-elements in the napA promoter are conserved, at least in dicotyledonous species.

Dr. Enno Krebbers, (Plant Genetic Systems N.V., Gent, Belgium) kindly provided the Agrobacterium strain C58C1(PMP90). Bertil Blom and Elisabeth Westergren are gratefully acknowledged for expert technical assistance. This work was supported by grants form the Swedish Natural Science Research Council, The Swedish Research Council for Forestry and Agriculture, The Swedish Institute and the Nilsson-Ehle Foundation.