Response of a nitrite-reductase 3.1-kilobase upstream regulatory sequence from spinach to nitrate and light in transgenic tobacco.

In the present study the question was addressed of whether the nitrite-reductase (NIR-)promoter from spinach (Spinacia oleracea L.), fused to a reporter gene (bacterial β-glucuronidase, GUS) and introduced into tobacco (Nicotiana tabacum L.) responds to nitrate and light in accordance with spinach (donor) or in accordance with tobacco (host). The data obtained at the GUS enzyme level as well as at the transcript level allow an unambiguous answer to this question: GUS gene expression under the control of the NIR-promoter from spinach responds to nitrate and light in accordance with the host (tobacco). Expression of the promoter-less GUS gene was not induced by any treatment.