Cis regulatory elements directing tuber-specific and sucrose-inducible expression of a chimeric class I patatin promoter/GUS-gene fusion

1617-4623

Class I patatin ; Promoter ; Cis-elements ; β-Glucuronidase

Springer Online Journal Archives 1860-2000

Biology

Summary The 5′-upstream region of the class I patatin gene B33 directs strong expression of the β-glucuronidase (GUS) reporter gene in potato tubers and in leaves treated with sucrose. Cis-acting elements affecting specificity and level of expression were identified by deletion analysis in transgenic potato plants. A putative tuber-specific element is located downstream from position −195. Nuclear proteins present in leaf and tuber extracts bind specifically to a conserved AT rich motif within this region. A DNA fragment between −183 and −143, including the binding site is, however, not able to enhance the expression of a truncated 35S promoter from cauliflower mosaic virus. Independent positive elements contributing to a 100-fold increase relative to the basic tuber-specific element are located between −228 and −195; −736 and −509, −930 and −736 and −1512 and −951. Sucrose inducibility is controlled by sequences downstream of position −228, indicating that the tuber-specific and sucrose-inducible elements are in close proximity.

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