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Loverine Taylor (right) has found a substance, kaempferol, that increases the
by Mary Aegerter
A pot of petunias could tell us a great deal about how to increase yields of corn and wheat. Loverine Taylor, associate professor of genetics and cell biology, is working with a system that might allow us to control fertility in plants. One aspect of fertility is how many offspring are produced. For plants, that starts with how many seeds—how many grains of wheat, how many kernels of corn. Taylor has found a substance, kaempferol, that increases the number of seeds in the petunia—and also in tomato, wheat, and corn. Taylor's work on plant fertility started with corn during a study of the accumulation of a pigment in response to various wavelengths of light. Her control plant was a mutant that lacked this pigment, as well as all other related compounds, and was white. It was also self-sterile: it could not pollinate itself, which corn usually can. A similar self-sterile white petunia mutant later joined the corn. For both mutants, it's only the pollen—the male part of the plant—that is sterile. The female parts of the reproductive system that receive the pollen are normal and will produce seed when pollinated by normal petunia pollen. Obviously these mutants aren't producing the increased yields, for they're not producing any seeds at all. The increased yields come when a normal petunia is treated prior to pollination with kaempferol, the substance that's missing from the sterile pollen. Kaempferol is a small, relatively simple molecule, one of many similar plant molecules called flavonoids. Flavonoids provide flower petals with color, among other things. Not only is kaempferol necessary for the production of fertile seed, but if you add a tiny amount of excess kaempferol to normal petunias—or corn or tomato or wheat—during pollination, you increase the seed yield by as much as 100 percent. But there's more to the flavonoid story. Although the purpose is uncertain, in stressful situations plants produce more flavonoids. Taylor's work has shown that some of these same flavonoids are also used in reproduction. This implied relationship between plant defense and plant reproduction is something she would like to have a lot of time to think about.
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