Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2007
Publication Date: 11/21/2007
Citation: Lewers, K.S., Turechek, W., Hokanson, S.C., Maas, J.L., Hancock, J.F., Serce, S., Smith, B.J. 2007. Evaluation of Elite Native Strawberry Germplasm for Resistance to Anthracnose Crown Rot Disease Caused by Colletotrichum Species. Journal of the American Society for Horticultural Science 132 (6):842-849.2007. Interpretive Summary: Wild relatives and ancestors of cultivated crops are valued as sources of important traits in crop variety development programs. One of the most important uses of this plant material is as parental sources of resistance to economically important diseases of cultivated crops. It is important to the scientists who develop new disease resistant crop varieties that the wild relatives are well characterized for several horticulturally important traits and are readily available. A collection of 38 wild relatives of strawberry has been especially well characterized and found to contain individuals that may be valuable sources of resistance to several pests and diseases. To determine if members of this collection may serve as sources of resistance to one of the most wide-spread and economically devastating strawberry diseases, anthracnose crown rot, the collection was evaluated for resistance to five isolates of the three species of the anthracnose-causing fungus, Colletotrichum. No single individual from the strawberry collection nor any group of individuals related by either ancestry or geographic region was found more resistant than any other, and no individual was resistant to all isolates of the fungus. However, many individual strawberry plants within these groups were identified as sources of resistance. Because these individuals have previously been shown to differ widely in horticultural characteristics as well as geographic adaptation, they will be valuable as sources of anthracnose resistance to strawberry scientists and growers from all strawberry producing regions of the world.
Technical Abstract: Anthracnose fruit and crown rots of strawberry (Fragaria ananassa) have been major disease problems in the southeastern strawberry producing regions of the United States since the early 1980s. Chemical controls are often inadequate, and few strawberry cultivars are resistant to this disease. Selection for cultivated genotypes is seen as a credible option for managing this disease. Only a small portion of F. ananassa germplasm has been screened for resistance to anthracnose fruit and crown rots. A subset (supercore) of the Fragaria core collection maintained at the U.S. Department of Agriculture National Clonal Repository, Corvallis, Ore., has been constructed to contain an elite group of native F. virginiana and F. chiloensis. This collection has been characterized for many horticultural traits, reactions to several common foliar diseases, nematode resistance, and black root rot resistance. Our objective was to evaluate the supercore collection for resistance to the three Colletotrichum species that cause strawberry anthracnose. No Fragaria sub-grouping was more resistant than any other, but rather individual genotypes within these groups were identified as sources from which resistance can be obtained. Colletotrichum isolates showed varying degrees of pathogenicity depending on the Fragaria genotype challenged. Apparent expression of resistance to anthracnose in genotypes from broadly different geographic origins, Chile, California, and Mississippi, and in two Fragaria species, suggests that there is a wealth of genetic resources in native octoploid germplasm. Also, collecting germplasm in areas of intense disease pressure may not be as beneficial as one might assume, at least where anthracnose disease is concerned. The strawberry supercore collection provides a selection of widely differing genotypes possessing horticultural attributes especially useful for future development of cultivars. The potential utility of this supercore collection has been and continues to be demonstrated.