Environs Prompt Advantageous Gene Mutations As Plants Grow; Changes Passed To Progeny

If a person were to climb a towering redwood and take a sample from the top and bottom of the tree, a comparison would show that the DNA are different. Christopher A. Cullis, chair of biology at Case Western Reserve University, explains that this is the basis of his controversial research findings.

Cullis, who has spent over 40 years studying mutations within plants, most recently flax (Linum usitatissimum), has found that the environment not only weeds out harmful and useless mutations through natural selection, but actually influences helpful mutations.

Cullis published his findings in the International Journal of Genetics and Molecular Biology and repeated them in the Journal of Visualized Experiments, where he challenged other scientists to repeat his experiment themselves.

Specifically, Cullis focuses on mutations involving the appearance of a small sequence of DNA known as LIS-1 and how the environment affects these changes.

The controversy stems from the idea that the environment changes organisms as they grow and these changes are passed on.

While originally accepted, the theory was eventually thrown out because science revealed that animals pass along DNA through their gamete or sex cells, which are not affected by the environment. This concept was assumed to be the same for plants, but Cullis's research says otherwise.

In his second study, three separate strands (the plastic strand, short strand, and tall strand) of the Stormont Cirrus variety of flax were grown under three separate conditions.

Each of the strands had been bred over multiple generations under different conditions: The plastic strand's ancestors were grown under control conditions, the short strand's ancestors were grown under low-nutrient conditions, and the tall strand's ancestors were grown under high-nutrient conditions.

The experiment showed each strand responded to each condition in a different way, corresponding to the environment its ancestors were grown in. The plastic strand outgrew the other strands under control conditions, the short strand outgrew the other strands when few nutrients were available, and the tall strand grew best when nutrients were readily available.