|Van Berkum, Peter|
Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2001
Publication Date: N/A
Technical Abstract: A total of 21,054 Fusaria, including 5610 F. oxysporum (Fo), were recovered from 1 conventional and 1 organic tomato field in Florida. A total of 410 Fo isolates were tested for pathogenicity on cv Bonny Best; 65 were pathogenic with 36 Fo lycopersici and 29 Fo radicis-lycopersici. Pathogenicity tests of these Fol on differential tomato cv 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. Group I (no cuts) contains 6 isolates, Group II (1 cut) 245, Group III (2 cuts) 24, and Group IV (3 cuts) 65. Group II contains 88.9% of root isolates including all the pathogenic isolates and 66.8% of the soil isolates. ITS region sequence data from representative isolates in each ITS group showed that pathogenic and nonpathogenic isolates in Group II were closely related, though in different clusters. Isolates in other groups had greater branch distances in a dendogram tree. Group II includes the well-characterized biocontrol strains CS-20, Fo47, and SA70.