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Title: The History of Public Breeding for Resistance to Cercospora Leaf Spot in North America

Author
item Panella, Leonard
item McGrath, Jon

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 3/27/2008
Publication Date: 2/26/2010
Citation: Panella, L.W., Mcgrath, J.M. 2010. The History of Public Breeding for Resistance to Cercospora Leaf Spot in North America. Book Chapter. In R.T. Lartey, J.J. Weiland, L. Panella, P.W. Crous, and C.E. Windels (ed.) Cercospora Leaf Spot of Sugar Beet and Related Species. APS Press, St. Paul, MN, U.S.A. 141-156.

Interpretive Summary: In the early 1920s efforts were being made to find sources of resistance to Cercospora Leaf Spot (CLS - caused by Cercospora beticola Sacc.), and in 1925, the United States Department of Agriculture - Agricultural Research Service, which was then called the Bureau of Plant Industries, began a resistance-breeding program to combat the devastation caused by CLS. Early on, progress in increasing CLS resistance was made through mass selection of open-pollinated, sugar beet varieties, however, due to the tremendous environmental variation in the intensity of CLS epiphytotics, it was realized that mass selection within open-pollinated varieties would not be effective. A program of inbreeding and progeny selection was used to develop CLS-resistant inbred parents for hybrids, synthetic varieties, and germplasm. Western North American germplasm developed by ARS breeders at Fort Collins, Colorado combined resistance to CLS with resistance to the Beet curly top virus. Eastern North American germplasm developed by ARS breeders at East Lansing, Michigan and Beltsville, Maryland combined resistance to CLS with resistance to Aphanomyces blackleg. Today, USDA-ARS plant breeders are working in ever-closer collaboration to provide new sources of CLS-resistant germplasm (mainly from the genetic resources within wild sea beet populations) in a rhizomania-resistant background. Because of the international importance of Cercospora leaf spot on sugar beet, resistance to this devastating and costly disease will remain a public breeding priority in the United States.

Technical Abstract: In the early 1920s efforts were being made to find sources of resistance to Cercospora Leaf Spot (CLS - caused by Cercospora beticola Sacc.), and in 1925, the United States Department of Agriculture - Agricultural Research Service, which was then called the Bureau of Plant Industries, began a resistance-breeding program to combat the devastation caused by CLS. Early on, progress in increasing CLS resistance was made through mass selection of open-pollinated, sugar beet varieties, however, due to the tremendous environmental variation in the intensity of CLS epiphytotics, it was realized that mass selection within open-pollinated varieties would not be effective. A program of inbreeding and progeny selection was used to develop CLS-resistant inbred parents for hybrids, synthetic varieties, and germplasm. Western North American germplasm developed by ARS breeders at Fort Collins, Colorado combined resistance to CLS with resistance to the Beet curly top virus. Eastern North American germplasm developed by ARS breeders at East Lansing, Michigan and Beltsville, Maryland combined resistance to CLS with resistance to Aphanomyces blackleg. Today, USDA-ARS plant breeders are working in ever-closer collaboration to provide new sources of CLS-resistant germplasm (mainly from the genetic resources within wild sea beet populations) in a rhizomania-resistant background. Because of the international importance of Cercospora leaf spot on sugar beet, resistance to this devastating and costly disease will remain a public breeding priority in the United States.