You are trying to identify DNA regulatory sequences that control the expression

Question

You are trying to identify DNA regulatory sequences that control the expression of a gene encoding a SAUR protein. The SAUR gene is expressed at high levels in auxin treated seedlings but at very low levels in untreated seedlings. You make the series of genes described below which each contain different lengths of the 5' gene flanking region. You transfer each gene into transgenic plants and measure its expression in auxin-treated and untreated seedlings. The following results are obtained.

You also fuse the following fragments to the minimal 35S promoter fused with the GUS gene. After transferring the genes into transgenic plants, you obtain the following results.

A.) Which part(s) or basepair regions of the flanking region is sensitive to auxin? Explain your reasoning.  

B.) Which part(s) or basepair regions of the flanking region is necessary for gene activation? Explain your reasoning

LENGTH OF THE 5 FLANKING REGION -1000 to -1 bp -800 to -1 bp -600 to -1 bp -400 to -1 bp -200 to -1 bp EXPRESSION OF THE MUTATED GENE AUXIN AUXIN

Explanation / Answer

A) The -200 to -1 bp and the -400 to -1 bp sequences are not sensitive to auxin as they are neither showing activity in the presence nor absence of Auxin. The longer fragments are showing expression in the presence of Auxin, thus the fragments from -400 to -600, -400 to -800 and -400 to -1000 fragments are sensitive to Auxin and express in its presence.

B) The 35S promoter region is required for the gene activation as in the presence of Auxin the fragment is showing gus activity.

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