Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: August 12, 2000
Publication Date: N/A
Technical Abstract: Nep1 is a phytotoxic protein that was purified from culture filtrates of Fusarium oxysporum. Gene constructs were designed to disrupt or enhance Nep1 expression. Transformation of Fusarium oxysporum f. sp. erythroxyli was carried out using polyethylene glycol-mediated techniques. Gene disruption transformants were identified by the lack of Nep1 production in liquid culture. Comparing their Nep1 production to wild type isolates in liquid culture identified transformants overexpressing NEP1. Transformation was verified using polymerase chain reaction techniques. The overexpression of Nep1 in F. oxysporum f. sp. erythroxyli results in approximately a 10-fold increase in Nep1 production in liquid culture at 25 C and stable production of Nep1 at temperatures (32 and 10 C) where Nep1 is minimally produced in wild-type isolates. Altering expression of Nep1 does not influence pathogenicity of F. oxysporum f. sp. erythroxyli based on root-dip assays. The influence of growth substrate on Nep1 production and plant pathogenicity will be discussed.