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In Context #17 (Spring, 2007, p. 5); copyright 2007 by The Nature Institute

Morphological Effects of Genetic Manipulation

As we reported in In Context #7 (http://natureinstitute.org/pub/ic/ic7/potatoes.htm), geneticist Johannes Wirz and his colleague Ruth Richter have been investigating whether genetic engineering affects the overall morphology and growth patterns of the manipulated plants. Johannes Wirz is a Nature Institute affiliate researcher, and he and Craig Holdrege have worked together over many years to understand and contextualize the results of modern genetics. (See, for example, their article, "Life Beyond Genes: Reflections on the Human Genome Project," in In Context #5: http://natureinstitute.org/pub/ic/ic5/genome.htm).

In a recent brief report on their project, Wirz and Richter summarize their results so far:

The genetic manipulation of the hereditary substance of potatoes, tomatoes, and summer wheat not only has the intended effect, but also alters the developmental dynamics, the form of the whole plant, the form of the leaves, and in wheat the architecture of the grain heads (spikelets). The photograph [see below] illustrates the unintended change. Again and again we see that the supposedly targeted manipulation affects the whole plant. (from Das Goetheanum, January 5, 2007, p.10; translation CH)

Even at the level of the genes unexpected things occur. In the case of the genetically modified tomatoes, the introduced gene (the so-called GUS gene) should be expressed in every cell of every plant. But this is not the case. In some plants gene expression is high, in others low and in still others gene expression is silenced altogether by the plant. Moreover, in different plants the gene construct has been integrated into different places in the plant's chromosomes.


genetically altered and
unaltered tomato plants

On the left two unmanipulated tomato plants; on the right, two genetically altered plants. All plants are about six weeks old and were grown under the same greenhouse conditions. The leaves of the genetically altered plant are rolled inwards at the margins and hang down more than those of the unmanipulated plants


tomato leaf sequences

Leaf sequences of above plants; top: unmanipulated plant; bottom: genetically altered plant. Every second leaf from the main stem of each plant was removed, pressed and then placed in sequential order (left: second leaf; right: last leaf). The leaves of the unmanipulated plants reach their biggest surface area at leaf 10, when the genetically altered leaves are already quite small. The leaves of the genetically altered plants are more deeply cut and have a more complicated leaf architecture.

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