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Unintended Effects of Genetic Manipulation
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Suppression of DHS enzyme in Arabidopsis (a mustard plant) was associated with enlarged leaves, greater root mass, and enhanced seed yield.

Manipulated Organism: Arabidopsis thaliana (Thale Cress; mustard family).

Inserted Transgenes: Arabidopsis gene DHS altered so that the gene would not be correctly expressed. To achieve this it was inserted in an antisense orientation. The antisense DHS gene was attached to the cauliflower mosaic virus (CaMV-35S) promoter so that the gene would be expressed in all parts of the plant.

Goal: Repress the expression of the enzyme DHS and examine the effects on growth and development in the experimental plant Arabidopsis. DHS catalyzes the conversion of lysine to deoxyhypusine, an unusual amino acid. DHS is thought to be present in all plant and animals cells. In unmodified Arabidopsis, DHS expression peaks in rosette leaves at days 14 and 35, coincident with bolting and leaf aging (senescence), respectively.

Intended Effect: Transgenic plants with suppressed DHS expression showed delayed bolting and delayed leaf senescence.

Unintended Effects: The transgenic plants had, unexpectedly, bigger rosette leaves, more root biomass, and enhanced seed yield. The authors state, "it is not clear at this juncture why suppression of DHS results in enhanced growth..." (p. 1234).

Additional Comments: This research is part of an effort to find ways to slow down aging in plants. Potential applications would be to produce transgenic vegetables and fruits that ripen more slowly to accommodate long transportation routes and to achieve longer shelf life. See similar study on DHS suppression in tomatoes.

Source: Wang, T., L. Lu, C. Zhang, C. Taylor et al. (2003). "Pleiotropic Effects Suppressing Deoxyhypusine Synthase Expression in Arabidopsis thaliana," Plant Molecular Biology vol. 52, pp. 1223-35.

Author Affiliations: Department of Biology, University of Waterloo, Canada.

Funding: Natural Sciences and Engineering Research Council of Canada (partial).

Product Status: Basic research; not on the market as of 2008.

Copyright 2008 The Nature Institute.

This document: http://natureinstitute.org/nontarget/reports/arabidopsis_002.php

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