CYP82E4-mediated nicotine to nornicotine conversion in tobacco is regulated by a senescence-specific signaling pathway

CYP82E4-mediated nicotine to nornicotine conversion in tobacco is regulated by a... Nicotine to nornicotine conversion in tobacco (Nicotiana tabacum L.) is regulated by an unstable converter locus which in its activated state gives rise to a high nornicotine, low nicotine phenotype in the senescing leaves. In plants that carry the high nornicotine trait, nicotine conversion is primarily catalyzed by a cytochrome P450 protein, designated CYP82E4 whose transcription is strongly upregulated during leaf senescence. To further investigate the regulation of CYP82E4 expression, we examined the spatiotemporal distribution and the stress- and signaling molecule-elicited expression patterns of CYP82E4 using alkaloid analysis and a fusion construct between the 2.2 kb upstream regulatory region of CYP82E4 and the β-glucurodinase (GUS) gene. Histochemical and fluorometric analyses of GUS expression revealed that the CYP82E4 promoter confers high levels of expression in the senescing leaves and flowers, and in the green stems of young and mature plants, but only very low activity was detected in the roots. In the leaves, GUS activity was strongly correlated with the progression of senescence. Treatments of leaf tissue with various signaling molecules including abscisic acid, ethylene, jasmonic acid, salicylic acid and yeast extract; and stresses, such as drought, wounding and tobacco mosaic virus infection did not enhance nicotine conversion or GUS activity in the green leaves, but an increase in CYP82E4 expression was observed in response to ethylene- or tobacco mosaic virus-induced senescence. These results suggest that the expression of CYP82E4 is senescence-specific in the leaves and the use of the CYP82E4 promoter could provide a valuable tool for regulating gene expression in the senescing leaves. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

CYP82E4-mediated nicotine to nornicotine conversion in tobacco is regulated by a senescence-specific signaling pathway

Loading next page...
 
/lp/springer_journal/cyp82e4-mediated-nicotine-to-nornicotine-conversion-in-tobacco-is-qpxG0n7U06
Publisher
Springer Netherlands
Copyright
Copyright © 2008 by Springer Science+Business Media B.V.
Subject
Life Sciences; Plant Pathology; Biochemistry, general; Plant Sciences
ISSN
0167-4412
eISSN
1573-5028
D.O.I.
10.1007/s11103-007-9280-6
Publisher site
See Article on Publisher Site

Abstract

Nicotine to nornicotine conversion in tobacco (Nicotiana tabacum L.) is regulated by an unstable converter locus which in its activated state gives rise to a high nornicotine, low nicotine phenotype in the senescing leaves. In plants that carry the high nornicotine trait, nicotine conversion is primarily catalyzed by a cytochrome P450 protein, designated CYP82E4 whose transcription is strongly upregulated during leaf senescence. To further investigate the regulation of CYP82E4 expression, we examined the spatiotemporal distribution and the stress- and signaling molecule-elicited expression patterns of CYP82E4 using alkaloid analysis and a fusion construct between the 2.2 kb upstream regulatory region of CYP82E4 and the β-glucurodinase (GUS) gene. Histochemical and fluorometric analyses of GUS expression revealed that the CYP82E4 promoter confers high levels of expression in the senescing leaves and flowers, and in the green stems of young and mature plants, but only very low activity was detected in the roots. In the leaves, GUS activity was strongly correlated with the progression of senescence. Treatments of leaf tissue with various signaling molecules including abscisic acid, ethylene, jasmonic acid, salicylic acid and yeast extract; and stresses, such as drought, wounding and tobacco mosaic virus infection did not enhance nicotine conversion or GUS activity in the green leaves, but an increase in CYP82E4 expression was observed in response to ethylene- or tobacco mosaic virus-induced senescence. These results suggest that the expression of CYP82E4 is senescence-specific in the leaves and the use of the CYP82E4 promoter could provide a valuable tool for regulating gene expression in the senescing leaves.

Journal

Plant Molecular BiologySpringer Journals

Published: Jan 15, 2008

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve Freelancer

DeepDyve Pro

Price
FREE
$49/month

$360/year
Save searches from Google Scholar, PubMed
Create lists to organize your research
Export lists, citations
Access to DeepDyve database
Abstract access only
Unlimited access to over
18 million full-text articles
Print
20 pages/month
PDF Discount
20% off