Genetic differences in clover make one ...( That clover necklace you make for yo...)

That clover necklace you make for your child could well be a ring of poison. Thats because some clovers have evolved genes that help the plant produce cyanide to protect itself against little herbivores, such as snails, slugs and voles, that eat clover. Other clover plants that do not make cyanide are found in climates with colder temperatures. So, in picking your poison, er, clover, ecology and geography play important roles.

A plant evolutionary biologist at Washington University in St. Louis is trying to get to the bottom of this botanical cloak and dagger tale. Kenneth Olsen, Ph.D., Washington University assistant professor of biology in Arts & Sciences, is looking at the genetics of a wide variety of white clover plants to determine why some plants do and some plants dont make cyanide what biologists call polymorphism, or two types.

We are documenting the effect of natural selection at the DNA sequence level to understand the molecular evolution of this polymorphism, said Olsen. Usually, researchers study model plants such as Arabidopsis or tobacco to understand genetics. But with clover we have a system where we can look in detail at DNA sequence variation and at the same time have a thorough understanding of the plants ecology.

In a study published the week of Sept. 24 in the journal Molecular Ecology, Olsen and his colleagues report findings on the molecular basis of the cyanide polymorphism.

Cyanide bomb in cell

White clover is native to Europe and Asia and was introduced some 300 years ago in North America. The cold factor-acyanogenic relationship has been known a long time in Europe and Asia and it re-evolved in North America when the plant was introduced, indicating that natural selection was a powerful force in shaping the geographical distributions of the two plant types.

The genetic basis behind cyanide production in clover plants boils down to just two genes.
'/>"/>