What Genes Help Blossoms Last Longer?
By Marcia Wood
May 24, 2010
Some cut flowers and potted plants are
better than others at fending off the aging process, known as senescence. To
help tomorrows blooms stay fresh longer,
Agricultural Research Service (ARS) plant
Jiang is investigating the gene-controlled mechanisms of plants' aging.
Such probing may eventually reveal how to modify flowers aging-linked
genes, or the proteins that are products of those genes.
Jiang is with the ARS
Pathology and Genetics Research Unit at Davis, Calif.
One approach, known as virus-induced gene silencing or VIGS, is
allowing Jiang and colleagues to determine the function of genes in aging
plants. In the laboratory, the scientists work with a naturally occurring
microbe known as the tobacco rattle virus, modifying it by inserting plant
genes of interest into it. In any given experiment, some flowering plants will
not be exposed to the virus, while others will be exposed to either the
unmodified or the modified virus.
Exposure triggers the plants natural defense mechanism, including
attempts to quash, or silence, the virus. When that happens, the genes that
were inserted into the modified virus are also silenced. By comparing all of
the plants, the researchers may be able to determine the newly-silenced
In early, proof-of-concept experiments, Jiang and
University of California-Davis
professor Michael S. Reid used petunia as their model plant. They showed that
inserting a piece of a color-imparting gene into the virus resulted in white
sectors or splotches on a normally purple-flowering petunia. The plants
defense system had silenced the genes normal function, which was to
create color, according to Jiang.
A second gene fragment that the team also inserted into the virus was
similarly silenced in the oddly white splotches. That silenced gene would
normally have been involved in producing ethylene, an aging compound. But the
white splotches on the plants exposed to the modified virus produced less
ethylene than unexposed plants, or plants exposed to the unmodified virus.
Though VIGS has been used elsewhere to study the functions of genes in
tomato and tobacco, the experiments by Reid and Jiang were the first to use
VIGS to explore senescence mechanisms in commercially grown cut flowers and
Reid, Jiang, and former graduate student Jen-Chih Chen describe their work
in the 2009 book Petunia:
Evolutionary, Developmental, and Physiological Genetics.
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.