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New Raspberries Use Virus Against Itself
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Raspberry lovers and growers—and the
environment—could benefit from genetically modified raspberries under
development by scientists with ARS and
Agritope, Inc., in Oregon.
The team, working under a cooperative research and development agreement, has
genetically modified Meeker raspberries to resist raspberry bushy dwarf virus
(RBDV) in laboratory and greenhouse tests. Meeker is the dominant variety of
raspberry in Washington, Oregon, and British Columbia, where 90 percent of
North American raspberries are grown.
"We're inserting parts of the virus' genetic material into the raspberry
plants to induce them to develop resistance to the disease," says ARS
virologist Robert R. Martin.
Martin works with ARS' Horticultural Crops Research Laboratory in Corvallis,
Oregon. Agritope is an agricultural biotechnology firm in Portland that uses
genetic engineering strategies to improve produce. The firm has already
successfully incorporated genes for other traits into several raspberry
cultivars.
Raspberries infected with RBDV develop smaller fruit that crumbles easily. That
makes the fruit unsuitable for use as whole berries in the fresh and frozen
markets. While they can still be used for juice or puree, the crumbly fruit
brings only about one-fourth the price per pound that growers get for fresh or
individually quick-frozen fruit.
Worse, within 5 years, a field becomes so infected with RBDV that growers must
take it out of production, remove the plants, fumigate the soil, and start
over. That means fewer domestic raspberries and higher costs for consumers.
"If the plants could naturally resist the virus, Northwest growers would
be more competitive in the world market because they wouldn't be out of
production every few years," Martin says. And the environment would
benefit from less chemical use. The scientists are trying three strategies to
find the best way to induce RBDV resistance.
One approach is to interfere with the virus' ability to replicate by inserting
a specific protein from the virus into the raspberry plant.
A second approach is to alter the viral gene that facilitates cell-to-cell
movement in plants and then insert that gene into plants. The virus would then
be able to infect one cell but the altered gene would prevent the virus from
spreading throughout a plant.
The third method they're trying is to have the plant make a small piece of
viral RNA, or genetic material, that does not make any protein. Through a
natural plant mechanism, this RNA then gets targeted by the plant for
degradation.
The researchers produced 25 plants of each of 300 transformed lines of Meeker.
Last spring, they put the plants outside to begin field-testing. Within 3
years, they'll know which genetic lines—and which strategy—will work
best. Then they can make the genetic material available to nurseries and plant
breeders. They should also be able to use the results to incorporate RBDV
resistance in other cultivars of raspberry, blackberry, or black raspberry.
The team has applied for a patent on their techniques.
"Because RBDV is so prevalent, many of the raspberries now in stores
naturally contain proteins from the virus. We're merely manipulating those
proteins for the plant's benefit," says Martin.—By
Kathryn Barry
Stelljes, Agricultural Research Service Information Staff.
This research is part of Plant Diseases, an ARS National Program (#303)
described on the World Wide Web at
http://www.nps.ars.usda.gov/programs/cppvs.htm.
Robert R. Martin is with the
USDA-ARS Horticultural
Crops Research Laboratory, 3420 N.W. Orchard Ave., Corvallis, OR 97330;
phone (541) 750-8794, fax (541) 750-8764. |
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"New Raspberries Use Virus Against Itself" was
published in the October 2000
issue of Agricultural Research magazine.
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Last Modified: 01/07/2002
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