That clover necklace you make for your child could well be a ring of poison.
That's 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 don't 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 plant's 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.
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