Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/16/2007
Publication Date: 7/18/2007
Citation: Liu, J., Bell, A.A., Wheeler, M.H. 2007. Molecular characterization of Fusarium oxysporum f. sp. Vasinfectum isolates recovered from cottonseed imported from Australia into California for cattle feed [abstract]. American Phytopathological Society Annual Meeting. Phytopathology. 97(7):S65.
Technical Abstract: Bell et al. recovered 17 Fusarium oxysporum f. sp. vasinfectum (Fov) isolates from cottonseed imported from Australia into California for cattle feed in 2003. These isolates and four isolates obtained from wilted plants in Australia by Kochman in 1994 are distinct from American Fov isolates in that they cause wilt following root dip inoculations, but not after stem puncture inoculations. We determined the genetic relatedness of these isolates with those found in the U.S.A. by sequencing fragments of the translation elongation factor 1-alpha, phosphate permase, and beta-tubulin genes and conducting phylogenetic and sequence analysis. The sequences in Kochman’s isolates were identical to those reported for a VCG01111 isolate from Australia. Seed isolate #23 had sequences similar to race 1. Seed isolates #5 and #17 from the largest VCG with 11 seed isolates clustered with race 3 isolates. Seed isolate #14, which complemented Kochman’s isolates in VCG tests and caused severe root rot and wilt of Deltapine 50 seedlings in the root dip assay, also clustered with race 3 isolates. However, a two base deletion feature in this isolate also loosely associated it with Australian VCG01111 isolates. Australian isolates related to race 3 may present a threat to the U.S. cotton industry, since they apparently survived fumigation treatments used on the imported seed.