Release No. 0305.95 Doris Stanley (301) 344-2963 Maria Bynum (202) 720-5192 USDA SCIENTISTS GENETICALLY ALTER SEEDLESS GRAPES WASHINGTON, April 11, 1995--U.S. Department of Agriculture scientists have achieved a scientific first by successfully inserting a new gene into Thompson Seedless grapes. Scientists hope the gene will give built-in protection against a common grape virus. The USDA research was collaborative with scientists at Cornell University and the University of Florida. "This genetic engineering breakthrough should ultimately decrease economic losses within the grape industry and reduce the amount of chemicals put into the environment," said Ralph Scorza, a horticulturist with USDA's Agricultural Research Service at Kearneysville, W.Va. He said the technique could pave the way for plant breeders to improve disease and insect resistance of all major grape varieties. Successfully inserting the new gene is the most important part of the research, Scorza said. He added that lab and field tests are planned to see if the gene defends against tomato ringspot, a virus that attacks grapevines and other woody plants. Scorza is part of a team ofscientists which put the gene into Thompson Seedless, America's most popular seedless grape. Healthy, genetically transformed grapevines are growing in greenhouses at Kearneysville. Other members of the research team are horticulturist David W. Ramming and plant physiologist Richard L. Emershad at the ARS Horticultural Crops Research Laboratory, Fresno, Calif.; plant pathologist Dennis J. Gray, University of Florida, Leesburg; plant pathologist Dennis Gonsalves, Cornell University, Geneva, N.Y.; and biological science lab technician John M. Cordts, who works with Scorza at the ARS Appalachian Fruit Research Laboratory in Kearneysville. Scorza said that an important part of the gene transfer work was the development by Ramming and Emershad of a special gel-like mix of nutrients to sustain immature grape embryos. Normally, these embryos, which would be the seed in most grapes, would not survive in seedless varieties. Scorza used Ramming and Emershad's growth medium to keep tissue-cultured grape plants alive and thriving. These plants were grown from grape embryos the size of a pinhead, produced at the University of Florida by Dennis Gray. Gray developed the embryos from leaves of Thompson seedless grapevines. Scorza and Cordts inserted into these embryos a gene for a protein present on the exterior or "coat" of tomato ringspot virus. The gene was isolated and cloned by Dennis Gonsalves at Cornell. Tomato ringspot is a virus, transmitted by microscopic worms called nematodes, that is especially severe in the eastern United States, said Gonsalves. After appropriate clearances by USDA's Animal and Plant Health Inspection Service, Scorza and Gonsalves plan to screen the new gene-carrying grapevines for resistance to tomato ringspot virus in greenhouse and field tests later this year. The scientific team predicts that these genetically transformed grapevines will lead the way to putting new genes into other grape varieties that could protect them from other diseases and pests. California is the nation's leading producer of Thompson Seedless and other grapes for the fresh market and for the raisin and wine industries. Each year, growers produce more than five million tons, valued at more than $1 billion. # NOTE TO EDITORS: Contact for details Ralph Scorza, Appalachian Fruit Research Laboratory, Agricultural Research Service, USDA, Kearneysville, W.Va. 25430, telephone (304) 725-3451; David W. Ramming and Richard L. Emershad, Horticultural Crops Research Laboratory, ARS, USDA, Fresno, Calif. 93727, telephone (209) 453-3160; Dennis J. Gray, University of Florida, Leesburg, Fla. 34748, telephone (904) 360-6686; or Dennis Gonsalves, Cornell University, Geneva, N.Y. 14456, telephone (315) 787-2334. Color slides are available from John Kucharski, ARS Audiovisual Branch, USDA, 6303 Ivy Lane, Greenbelt, MD, 20770-1433, telephone (301) 344-2900.