Location: Horticultural Crops Research
2013 Annual Report
There is high demand for everbearing or remontant strawberries with very high fruit quality and resistance to soil pathogens that cause serious diseases like root rot; however, their development through conventional methods has been slow due to environmental influences on the expression of remontancy, limited sources of genetic variability and the need to conduct controlled disease inoculations. Strawberry breeders in California, Florida, Michigan, New Hampshire and Oregon evaluated an extensive array of germplasm to serve as a template for discovery of genes responsible for fruit quality and development. Over 900 individuals were evaluated, including old and new cultivars, wild plants from North and South America, elite breeding parents, and experimental crosses from the Netherlands, United Kingdom, Spain, France and the United States. A genetic test was developed to predict resistance to one of the sources of root rot resistance. This genetic test enables breeders to identify seedlings that have this source of resistance without the need to carry out the expensive, time-consuming disease inoculation tests.
As a result of genetic testing of strawberry selections in the USDA-ARS Corvallis and Michigan State University breeding programs and extensive phenotypic measurements of these strawberries: • 42 individuals from 13 crosses were discarded as DNA markers identified them as derived from unintended parentage • Multiple clones representing three important cultivars used as parents were identified. Genetic testing is necessary to identify the correct parent and get the intended cross. • Fourteen strawberry selections were identified as having new sources of resistance to red stele and will be evaluated for other traits important in breeding strawberries. • Two interspecific hybrids of wild strawberries were found which are strongly remontant in multiple environments (California, Michigan and Oregon). These will provide breeders with a unique source of genes for repeat flowering. • This extensive data set is being mined and will continue to generate genes of importance for strawberry breeding. These efforts will serve as the basis for the identification of superior parents using the newly developed marker assisted breeding applications.