Plant Molecular Biology 38: 785-795 (1998)

Ethylene responsive element binding protein (EREBP) expression and the transcriptional regulation of class I ß-1,3-glucanase during tobacco seed germination

Gerhard Leubner-Metzger, Luciana Petruzzelli (1), Rosa Waldvogel, Regina Vögeli-Lange (2), Frederick Meins, Jr.

Glucanase promoter Figure 3. Deletion analysis of the the Glb promoter in germinating Havana 425 tobacco seeds.

(a) GUS activity (fkat/seed) of control seeds.

(b) Downregulation by 10 μM ABA expressed as % GUS activity relative to the corresponding control populations of seeds shown in (a).

Seeds of a Glb-GUS promoter deletion series with 5 independent transformants for each deletion were imbibed in continuous light with and without 10 μM ABA. Extracts were prepared from seeds after 3 days when ca. 70 % of controls and none of ABA treated seeds had ruptured endosperms. The extracts were assayed for GUS activity. For each construct, bars in the same relative position represent seed of the same independent transformant shown in the order: 2 high-, 2 medium-, and 1 low-expressing line as judged from tests of the transformants described by Vögeli-Lange et al. [44]. Each bar represents the mean value, usually of replicate assays, in two independent experiments. The numbers above the bars are the median value obtained with each deletion.

(c) Diagram illustrating regions of the Glb promoter relevant to regulation in germinating seeds.

Filled boxes: The distal region (-1452 to -1193) important for high-level expression and ABA down-regulation; the proximal region -402 to -211 necessary and sufficient for low-level expression in the micropylar endosperm; and, the proximal region downstream of - 402 that may also contribute to ABA downregulation.

Symbols: ARE, an ABA-responsive element (TAACAAA) important for down-regulation by ABA of a-amylase genes in barley endosperm [15]; AGC, one copy in inverse orientation of the AGC box (AGCCGCC) present as two copies (-1346 and -1314) in the ERE [16]; EM, an EM box (TGTAAAG) important for endosperm-specific expression of cereal storage-protein genes in tobacco [4]; and, ERE, the Glb ethylene-responsive element [30]. Numbers refer to position relative to the start of transcription.

Hyperlink to drawing of the tobacco class I ß-1,3-glucanase B (GLB) gene promoter
Article in PDF format (2.1 MB) Abstract          Fig. 1          Fig. 2          Fig. 3          Table 1          GLB-promoter  

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