U.S. Water News Online
RIVERSIDE, Calif. -- University of California, Riverside
researchers reported the development of technology that increases
crop drought tolerance by decreasing the amount of an enzyme that is
responsible for recycling vitamin C.
Biochemist Daniel R. Gallie, a professor of biochemistry at the
University of California, Riverside together with Zhong Chen of his
research group reported their findings in the May issue of The Plant
In the study, the authors reasoned that decreasing the amount of
the enzyme dehydroascorbate reductase or DHAR would reduce the
ability of plants to recycle vitamin C, making them more drought
tolerant through improved water conservation. The researchers
accomplished this by using the plant's own gene to decrease the
amount of the enzyme three fold.
Researchers used tobacco as a model for crops that are highly
sensitive to drought conditions.
"However, our discovery should be applicable to most if not all
crop species as the role of vitamin C is highly conserved among
plants," said Gallie. In work published last year in the Proceedings
of the National Academy of Sciences, Gallie and his research team
reported that the level of vitamin C could be boosted by increasing
the amount of this same enzyme.
The U.S. Department of Agriculture and California Agricultural
Experiment Station funded the six years of research that led to the
Vitamin C serves as an important antioxidant in plants as it does
in humans and among its many functions in both, it destroys reactive
oxygen species that can otherwise damage or even kill cells. "Once
used, vitamin C must be regenerated otherwise it is irrevocably lost.
The enzyme dehydroascorbate reductase, or DHAR, plays a critical role
in this recycling process," explained Gallie.
Reactive oxygen species are produced in plants typically following
exposure to environmental conditions such as drought, cold, or air
pollution. Plants sense drought conditions by the buildup in reactive
oxygen species and then respond by reducing the amount of water that
escapes from their leaves. Reducing the amount of DHAR decreases the
ability of the plant to recycle vitamin C, thus reducing the ability
to eliminate the buildup in reactive oxygen species that occurs with
the onset of a drought.
"This reduction in vitamin C recycling causes plants to be highly
responsive to dry growth conditions by reducing the rate of water
that escapes from their leaves. Thus, they are better able to grow
with less water and survive a drought," said Gallie.
"Through use of this technology, we are helping crops to conserve
water resources. In a way, we are assisting them to be better water
managers, which is important for crops growing in areas that can
experience erratic rainfall," he added. "This discovery will assist
farmers who depend on rainwater for their crops during those years
when rainfall is low. It will also assist farmers who irrigate their
crops to conserve water, which is important in a state like
California where rapid population growth continues to increase the
demand on this scare resource. Finally, this discovery should help
farmers who grow crops in arid areas, such as exists in many
Source: AgBioView Newsletter
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