Discovery of 'master switch' for the communication process between chloroplast and nuclei...( rived signals within the chloroplast. T...)

Many of the nuclear genes that encode chloroplast proteins are regulated by a "master switch" in response to environmental conditions. This "master switch," like a binary computer, can activate or de-activate certain sets of genes based on stress signaling processes.

"One of our suggestions in the paper is that ABI4 seems like a prime candidate to be the master switch," Koussevitzky said. "ABI4 binds to a newly identified sequence motif, and by doing so prevents light-induced regulatory factors from activating gene expression. It has a role in so many signaling processes in the plant, it might actually be the master switch that researchers have been looking for."

The discoveries are critical to future research efforts in designing new generations of plants, Mittler said.

"A lot of things that occur in the chloroplast are important for production, for growth, for response to the environment," he said. "So this is a very basic mechanism of communication between the chloroplast and the nucleus. It had been previously suggested that the elements in this process go through multiple pathways. This work shows that the elements actually go through this one particular route.

"Now we are in much better shape in solving the question of generating plants that can use marginal water, or marginal soil, and do so in a way that the plant wont completely suppress its normal metabolisms and activate all of its stress metabolisms when faced with a lot of stress. If you want to generate a plant that is more tolerant, you need to deal with these two things."

Added Koussevitzky: "Were trying to put the signaling pathways in the context of the plants stress response. It will take a little more tweaking, but at least knowing that it is going through a certain particular pathway will enable researchers
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Contact: John Trent
jtrent@unr.edu
775-784-4959
University of Nevada, Reno
2-Apr-2007