Fall 2007.
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New & Now: Fall 2007

Infectious Affection

Weathering the Storm

Petite Performer

Unlikely Presence

Into the Blue

Frog Friendly

The Ion Channel

Plaques and Tangles

Closer Look


Illustration by Hannah Stouffer.

Into the Blue

What Makes Plants Bend Toward the Light?

As seedlings push through the ground, their stems grow in the direction of actinic light, the blue region of the electromagnetic spectrum. Plant scientists refer to this phenomenon as a "positive phototropic response."

Plants adapted for vigorous phototropic responses are better positioned to take advantage of available solar energy, thus giving them a significant evolutionary leg up. Some of the most successful phototropic responders, weeds in your lawn for example, aren't terribly useful. But what if their hunger for solar energy could be genetically transferred to more desirable crops, wheat or maize perhaps?

Mannie Liscum, a professor of biological sciences, and MU doctoral student Ullas Pedmale are among those scientists who believe such an outcome would be valuable indeed. "By understanding how phototropism works at a molecular level, we can... optimize plants' ability to capture light for photosynthesis, which would result in more energy capture and the growth, of potentially agronomically useful biomass," says Liscum.

In a recent study, Pedmale and Liscum discovered that NPH3, a protein essential in plants' bending toward actinic light, was phosphorylated, or had a phosphate group attached, in seedlings grown in darkness. When test plants were exposed to light, they became dephosphorylated, or lost their phosphate group.

Pedmale and Liscum determined it was the absorption of light by a photoreceptor protein, "phot1," that cued NPH3 proteins to lose the phosphate group and jump-started "phototropic signaling." The finding, Liscum says, brings scientists one step closer to unraveling the signalling process, the stunningly complex means by which plants detect directional blue light and transform it into the chemical signals that inform them which way to bend.

The study, undertaken with funding from the National Science Foundation, appeared in the July 7 edition of the Journal of Biological Chemistry.

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Published by the Office of Research.

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