In a study published in the Sept. 24 issue of the journal Science, the researchers describe how a gene called phytochrome-interacting factor 1, or PIF1, affects the production of protochlorophyll, a precursor of the chlorophyll used by plants to convert the sun's energy into food during photosynthesis.
While a seed germinates under soil, in the dark, it is producing a controlled amount of protochlorophyll in preparation for its debut above ground. Much like a baby takes his or her first breath of air after emerging from the womb, seedlings must quickly convert protochlorophyll into chlorophyll once they are exposed to light for the first time.
"It's a delicate balancing act," said Peter Quail, professor of plant and microbial biology at UC Berkeley's College of Natural Resources and principal investigator of the study. "The young plant needs some protochlorophyll to get the ball rolling in photosynthesis. But if the plant accumulates too much of the compound, it leads to photo-oxidative stress, which is seen as bleaching on the leaves. The overproduction of protochlorophyll is like a ticking time bomb that is set off by the sun."
Quail is also research director of the Plant Gene Expression Center, a joint research center of the Agricultural Research Service of the U.S. Department of Agriculture and the University of California.
The researchers targeted the PIF1 gene because it binds to phytochrome, a protein that is triggered by light and that controls a plant's growth and development. The researchers disabled the PIF1 gene in the species Arabidopsis thaliana, a mustard plant, and compared the mutant seedlings with a co
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Contact: Sarah Yang
scy@pa.urel.berkeley.edu
510-643-7741
University of California - Berkeley
23-Sep-2004