Germplasm resources for verticillium wilt resistance breeding and genetics in strawberry (Fragaria)

BACKGROUND: The fungal disease verticillium wilt has been recognized as an obstacle to strawberry production since its initial description in 1931. The full potential of genetic resistance as a solution to this problem has yet to be determined or realized. OBJECTIVE: Our investigations are concerned with defining new sources of resistance to verticillium wilt disease in cultivated and wild strawberry germplasm, and with advancing genetic studies on the basis of resistance/susceptibility. METHODS: We screened 23 diploid, 1 decaploid, and 26 octoploid Fragaria (strawberry) germplasm accessions and cultigens for response to root-dip inoculation with Verticillium dahliae isolate V1. Pedigree relationships of 10 studied cultigens were examined. Crosses were performed between resistant and susceptible accessions. RESULTS: Variability in inoculation response existed within and between species at diploid and octoploid levels. Very or moderately resistant accessions were found within each of three diploid and three octoploid species. Moderately or very susceptible accessions were documented within F. vesca and each octoploid species. Segregation for resistance/susceptibility was evident in progeny populations. CONCLUSIONS: The verticillium wilt resistance ratings reported here and discussed in relation to prior studies adds to the body of publically available knowledge about sources of wilt resistance and susceptibility in Fragaria germplasm.