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A Unique Potato Virus Collection


  If a plant pathologist, breeder, geneticist, or grower discovered an unusual viral disease in a potato crop, where could that person go to identify the culprit?


One good place to check would be the Agricultural Research Service's Schultz Potato Virus Collection, named after ARS plant pathologist Erwin S. Schultz. He and plant pathologist Donald Folsom, with the Maine Agriculture Experiment Station, started this collection in 1916 at Aroostook State Farm at Presque Isle, Maine.


Researchers throughout the world have compared their infected potato plants with those maintained in the Schultz collection. Even now—after more than 80 years—the collection still contains progeny from the original infected plants.


Names given to the infectious diseases maintained in the collection were based on descriptive symptoms of so-called degeneration diseases of potato hosts. Scientists showed that diseases such as Aucuba mosaic, calico mosaic, latent virus, leaf rolling mosaic, mild mosaic, rugose mosaic, and severe mosaic are viral in nature.


In 1971, ARS researchers determined that a viroid was the cause of potato spindle tuber disease, which previously had been identified as a virus. Materials from the Schultz potato virus collection were used to identify these pathogens.


Plant pathologist Robert W. Goth, who has been curator since 1968, maintains the collection, now housed at Aroostook Farm and at ARS' Vegetable Laboratory in Beltsville, Maryland.


"Since 1930, viral reactions of many potato cultivars released jointly by USDA and cooperating agencies were evaluated using samples from this collection," says Goth.


Viruses are maintained in plants grown in insect-proof cages to avoid contamination and loss of original viruses. Each year, the virus-infected plants are grown out in these small, screened cages in the field to keep the collection going for future use. Goth saves four tubers from each cage for replanting at Presque Isle the next year and sends the remaining tubers to Beltsville for further use and study. All of the potato viruses in the collection are those most prevalent in the United States, Canada, and Europe.


"Interestingly," says Goth, "some pathogens in the collection affect not only potatoes, but other crops as well." Potato virus Y, for example, which can be spread by aphids, also affects tobacco, tomatoes, peppers, and many other plants.


"The collection continues to grow," Goth notes. A new Carla virus—isolated from the potato variety Red Lasoda in 1992 and named "potato latent virus" in 1998—was added to the collection this year. Researchers can request samples of any virus in the collection.—By Tara Weaver-Missick, Agricultural Research Service Information Staff.


Robert W. Goth is with the USDA-ARS Vegetable Laboratory, Rm. 240, Bldg. 10A, 10300 Baltimore Ave., Beltsville, MD 20705-2350; phone 301-504-5953, fax 301-504-5555.


"A Unique Potato Virus Collection" was published in the March 2000 issue of Agricultural Research magazine.




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