While it may taste good on a hot dog, mustard's spice is actually a form of chemical warfare - a tangy bit of self-preservation mustard plants mount to discourage hungry insects. But, as any mustard aficionado knows, there's diversity in that defense: Even wild mustard plants of the same species have an array of distinct flavors.
Recently, a team of scientists led by Duke evolutionary geneticist Tom Mitchell-Olds pieced together the genetic tweaks that explain those variations. Studying wild mustard plants grown in separate parts of the Rocky Mountains, Mitchell-Olds and his colleagues identified two key changes in a spice-controlling enzyme that have allowed plants to custom-tailor their spicy defenses to their environment. While the finding may have some practicial implications for plant breeders, it's also the first time scientists have been able to construct a complete picture of how complex traits evolve in response to environmental pressure.
"We finally have the tools to find the genes and to understand their influence on physiology and fitness," says Mitchell-Olds, a professor of biology and member of Duke's Institute for Genome Science and Policy, "and that's pretty cool." Or, as the case may be, hot.