Upstream sequences regulating legumin gene expression in heterologous transgenic plants |
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Authors: | Helmut Bäumlein Wout Boerjan Istvan Nagy Reinhard Panitz Dirk Inzé and Ulrich Wobus |
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Institution: | (1) Zentralinstitut für Genetik und Kulturpflanzenforschung, Akademie der Wissenschaften, O-4325 Gatersleben, Germany;(2) Laboratorium voor Genetica, Rijksuniversiteit Gent, B-9000 Gent, Belgium;(3) Agricultural Biotechnology Center, H-2102 Gödöllö, Hungary |
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Abstract: | Summary We have previously isolated a legumin gene LeB4 from Vicia faba and shown that a 4.7 kb DNA fragment containing the gene leads to seed-specific expression in transgenic tobacco plants. Here we report that the 2.4 kb upstream sequence alone, when fused to either the neomycin phosphotransferase II (nptII) gene or the -glucuronidase (uidA) gene, leads to high enzyme levels in transgenic seeds of both tobacco and Arabidopsis. -Glucuronidase (GUS) activity is especially intense in the cotyledons fading out towards the embryonal root tip, a result confirmed by in situ hybridization. Staining of endosperm cells is consistent in both species. Analysis of a series of promoter deletion mutants fused to the nptII gene and introduced into tobacco plants revealed that about 1 kb of 5-flanking sequence is sufficient for high-level expression but indirect evidence suggests the presence of weak positive regulatory elements further upstream. Deletions leaving only 0.2 kb of upstream sequence reduce enzyme levels to less than 10%. A deletion which destroys the legumin box with its seed protein gene-specific CATGCATG motif has no obvious effects on expression levels. |
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Keywords: | Faba bean legumin gene Plant gene regulation Transgenic plants Seed-specific expression |
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