The study, published in the June 19 issue of Nature, was led by Salk professor and Howard Hughes Medical Institute Investigator Joanne Chory and Salk/Howard Hughes Medical Institute postdoctoral fellow Pablo Cerdn. "The mechanism that leads to plants flowering early in response to shaded conditions has largely been unknown," said Chory. "And this is a major problem for crops, which are planted at high density and often shade each other in the field. By understanding this process, we may someday be able to control plant flowering responses to shade and, in turn, increase the yield of crops."

The Salk researchers focused on what is known in plants as the "shade-avoidance syndrome." When plants grow in high density, they perceive a decrease in the relative amounts of incoming red light to light of other wavelengths. This change of light serves as a warning for competition, prodding the plants to flower and create seeds. The byproduct of this process is that plant stems grow longer and leaf volume declines, leading to decreases in biomass and yield.

To understand the biology behind this process, the Salk scientists looked at a group of phytochromes, photoreceptors in plants that trigger the "shade-avoidance response." Using the common mustard seed plant Arabidopsis-the first plant to have its entire genome sequenced by a multinational consortium that involved Salk professor Joe Ecker and other researchers-Chory and Cerdn identified the specific protein that triggers flowering in response to suboptimal light conditions.

"We screened for mutant versions of Arabidopsis to identify the protein and the signaling pathway that leads to flowering in shade conditions," said Cerdn. "We discovered that the protein, called PFT1, acts
'"/>

Contact: Robert Bradford
bradford@salk.edu
858-453-4100 x1290
Salk Institute
1-Jul-2003