The nitrate reductase promoter of birch directs differential reporter geneexpression in tissues of transgenic tobacco

A 1535 bp promoter of the nitrate reductase gene (nia) from birch (Betula p endula) and a series of 5' deletions were fused to the beta-glucuronidase ( GUS) gene and introduced into Nicotiana plumbaginifolia. In transgenic plan ts the NR promoter sequences directed strong GUS expression in the root epi dermal hair cells, and in phloem cells of leaf and stem vascular tissue. Th e NR promoter confers also a significant stimulation of the GUS gene expres sion by nitrate. These findings might indicate that nitrate flow is one of the signals involved into tissue and cell specific expression of the NR pro moter GUS fusions.