Melon-Like Cukes Have Key Disease Resistance

Why can't a cucumber be more like a melon and vice versa? It could, say Agricultural Research Service scientists who studied a wild Chinese cuke that's genetically similar to a melon.

ARS researchers have produced the first genetic cross between an exotic wild-type Chinese cucumber and a Chinese commercial type. The wild germplasm was provided by a visiting Chinese scientist who worked in ARS' Vegetable Crops Research Unit in Madison, Wisconsin.

The offspring are sterile, but with further genetic manipulation new hybrids may serve as a genetic bridge between a cucumber and a melon. That's good news for breeders because melons have disease resistance genes that cucumbers lack and vice versa.

To find new sources of resistance and other economically important traits in cucumbers and melons, ARS plant geneticists collected new germplasm from India in 1992 and China in 1994.

They found that the germplasm from India and China holds new genetic diversity not previously available to U.S. breeders. Yet another key finding: The germplasm from India differed greatly from that collected in China.

The U.S. national germplasm collection of cucumbers and melons is at ARS' North Central Regional Plant Introduction Station at Ames, Iowa. Before 1992, 10 percent of the cucumber germplasm in that collection was from India. The new accessions are important additions to the U.S. germplasm collection.

Scientific contacts: Jack E. Staub, Vegetable Crops Research Unit, Agricultural Research Service, USDA, University of Wisconsin, Madison, WI, (608) 262-0028 or 264-5193, fax (608) 262- 4743 E-mail: jestaub@facstaff.wisc.edu or Dr. James D. McCreight, Research Leader, Crop Improvement and Protection Research Laboratory, Agricultural Research Service, USDA, Salinas, CA (408) 755-2864, fax (408) 755-2814, E-mail: jmccreig@asrr.arsusda.gov