Submitted to: World Cotton Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/3/2007
Publication Date: 9/10/2007
Citation: Liu, J., Bell, A.A., Wheeler, M.H., Stipanovic, R.D. 2007. Molecular characterization of Fusarium oxysporum f. sp. vasinfectum isolates from cottonseed imported from Australia into California for dairy feed [abstract]. Proceedings of World Cotton Research Conference, September 10-14, 2007, Lubbock, Texas. 2007 CDROM. Interpretive Summary:
Technical Abstract: Bell et al. recovered 17 Fusarium oxysporum f. sp. vasinfectum (Fov) isolates from cottonseed imported from Australia into California for dairy 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. by sequencing fragments of the translation elongation factor 1-alpha (EF-1 alpha), phosphate permase, beta-tubulin genes, and mating type genes and by conducting phylogenetic and sequence analysis. One of Bell’s seed isolates, AustSeed 14, which is as aggressive as Kochman’s isolates and vegetatively compatible with Kochman’s isolates, belonged to race 3 lineage. Eleven of the 17 seed isolates also belonged to race 3 lineage and formed a vegetatively compatible group. One seed isolate belonged to race 1 lineage but is not vegetatively compatible with the U.S. race 1 lineage isolates. The remaining four seed isolates (called the AustSeed 1 group) do not belong to any known race lineages. Furthermore, indel analysis of the EF-1 alpha gene sequences revealed a close evolutionary relationship among AustSeed 14 isolates, Kochman’s Australian isolates and the four AustSeed 1 group seed isolates. Race 3 isolates favors alkaline clay soil and do not require nematodes to cause severe disease; this is also true for Australian biotypes. Australian seed isolates may present a significant threat to the U.S. cotton industry.