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