La Jolla, CA - Scientists have identified three different signals that indicate damage to chloroplasts the photosynthetic factories of plant cells that give plants their green color but little is known about how the signal gets passed on to the nucleus. Scientists at the Salk Institute for Biological Studies made a big step towards explaining how chloroplasts let a cell's nucleus know when things start to go wrong at the periphery so nuclear gene expression can be adjusted accordingly.
Multiple distress signals converge on a single pathway and channel the information to a nuclear master switch, the scientists report in the March 29 issue of Science Express. In response, hundreds of genes involved in photosynthesis are simultaneously shut off to ease the chloroplast crisis.
Plants store the bulk of their genetic information in the nucleus but chloroplasts and mitochondria, which act as cellular power plants, share some of the responsibility. Yet, chloroplasts and mitochondria contain thousands of imported proteins, which need to work hand in hand with the few that are encoded in the nucleus and others made locally.
"Such an arrangement requires a tightly coordinated communication between organelles and the nucleus but not much is known about the signaling pathways between chloroplasts and the nucleus says the study's lead author, Joanne Chory, Ph.D., professor and director of the Plant Biology Laboratory and investigator with the Howard Hughes Medical Institute.
The basis of the study may provide insight into other areas of biological research. The importance of an unhindered flow of information to and from cellular organelles, for example, is illustrated by some types of cancer, in which the breakdown in communication between mitochondria and the nucleus contributes to the progression of tumors.
The green chlorophyll in chloroplasts absorbs light's energy, which not only results in the release of oxygen but is
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Contact: Gina Kirchweger
kirchweger@salk.edu
858-453-4100, ext. 1340
Salk Institute
29-Mar-2007