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Unintended Effects of Genetic Manipulation
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Plants producing a biodegradable polyester were smaller, never produced seeds and showed severe changes in metabolism.

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

Inserted Transgenes: Three genes derived from bacteria that are needed for polyhydroxybutyrate (PHB) production, which is a biodegradable polyester, were transferred into the mustard Arabidopsis. The gene was fused to the cauliflower mosaic virus (CaMV-35S) promoter so that the genes would be expressed in all parts of the plant.

Goal: Transgenic plants that produce a biodegradable polyester.

Intended Effect: Six transgenic lines did accumulate PHB in their chloroplasts. The greatest amount of PHB was 4% of total plant fresh weight.

Unintended Effects:
  • The more PHB in a transgenic line, the smaller the plants grew. Growth retardation was evident even in those plants that accumulated very little PHB.
  • The plants with the most PHB never produced seeds.
  • The plants showed slight chlorosis (yellowing of leaves).
  • Metabolic profiling of sixty metabolites suggested that "severe changes in metabolism result from the production of PHB in these lines" (p. 845). The amounts of sugars, alcohols, amino acids and organic acids changed markedly while-to the surprise of the researchers-the amounts and composition of fatty acids did not change.

Source: Bohmert, K., I. Balbo, J. Kopka, V. Mittendorf et al. (2000). "Transgenic Arabidopsis Plants can Accumulate Polyhydroxybutyrate to Up to 4% of Their Fresh Weight," Planta vol. 211, pp. 841-45.

Author Affiliations: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam, Germany; University of Fribourg, Switzerland; University of Lausanne, Switzerland; Freie Universität Berlin, Germany.

Funding: German Ministry of Agriculture (partial).

Product Status: Not on the market as of 2008.

Copyright 2008 The Nature Institute.

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