Now, for the first time, scientists have obtained a detailed map of one of biology's most important light detectors, a protein found in many species across life's plant, fungal, and bacterial kingdoms. By resolving the three-dimensional structure of the protein known as phytochrome, scientists can now tease out the secrets of how plants, in particular, react to light, opening the door for a host of manipulations that could have sweeping implications for agriculture.
Writing in the Nov. 17, 2005 issue of the journal Nature, a team of scientists from the University of Wisconsin-Madison report that they have obtained the crystal structure of a phytochrome from a bacterium, the first such light-gathering structure depicted for all of biology. The structure of the bacterial phytochrome, according to the report, suggests its architecture first arose a billion or so years ago in a common ancestor and is shared among not only bacteria, but also by plants and fungi.
"This is probably the most important light regulator in agriculture," says Richard Vierstra, a UW-Madison plant geneticist and one of two collaborating senior authors of the Nature paper. "It tells plants when to germinate. It tells them where to grow to absorb the most light and to avoid competition. It tells them when to flower. It tells them when to die at the end of the growing season."
The accomplishment of the Wisconsin researchers, including first author graduate student Jeremiah Wagner, caps a 30-year quest by biologists to drill down to the inner workings of how plants, fungi and bacteria use light to guide their development. It will likely spur a rush by scientists to capitalize on the new knowledge and may one day lead to such things as plants whose growth, flowering and death can be precisely manipulated.