|Van Berkum, Peter|
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2001
Publication Date: N/A
Technical Abstract: Fusarium wilt in tomatoes, caused by Fusarium oxysporum f. sp. lycopersici is managed by soil fumigation with methyl bromide. Nonpathogenic Fusaria can reduce Fusarium wilt on several crops, including tomato, while most Fusaria in soil are saprophytic. Currently, plant bioassays are necessary to distinguish among pathogenic, beneficial and saprophytic Fusaria, while the genetic relationships among these Fusaria is unclear. This research was undertaken to characterize the population structure of Fusaria in tomato production soils with the long-term goal of identifying genetic markers for biocontrol ability. A total of 21,054 Fusaria, including 5610 F. oxysporum (Fo), were recovered from a conventional and an organic tomato field in Florida. A total of 410 Fo isolates were tested for pathogenicity on tomato; 65 were pathogenic with 36 Fo lycopersici and 29 Fo radicis-lycopersici. Bioassays of these Fol on differential tomato cultivars indicated 15 were Race 1, 6 Race 2, 5 Race 3, and 8 uncertain. The rDNA internal transcribed spacer region (ITS1-5.8S RNA gene-ITS2) was amplified from selected Fo isolates, digested with MspI, and 340 isolates grouped by Msp I band polymorphism.