The research team, which included Howard Hughes Medical Institute investigator Joanne Chory along with Detlef Weigel of The Salk Institute, published its study in Nature Genetics.

Arabidopsis is a small flowering plant that is widely used by plant scientists as an experimental organism because it is easily grown, prolific, and has the smallest genome of any flowering plant. Last year, researchers announced sequencing of the entire Arabidopsis genome.

Chory, Weigel and their colleagues sought to understand the natural variation in light sensitivity in Arabidopsis by studying 141 varieties of the plant gathered from different geographic locations. In their experiments, they exposed germinating seedlings of all of the plants to the same levels of blue, red, or far-red light, as well as to white light and to total darkness. The exposure to different light wavelengths was intended to reveal variation in signaling pathways known to be sensitive to those wavelengths. The scientists also exposed seedlings to two plant hormones known to affect light-sensitive pathways.

By measuring the length of the embryonic shoot, or hypocotyl, in the plants, the scientists could quantify each plants sensitivity to light. Hypocotyls tend to extend longer in lower light -- as the plant delays full germination so their length under standard light conditions reflects the plants sensitivity to light.

These experiments revealed substantial variation in light sensitivity across the varieties, found Chory, Weigel and their colleagues. The experiments showed that varieties from lower latitudes, where light is more intense, tend t
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
29-Nov-2001