Mutation of an arginine biosynthesis gene causes reduced pathogenicity in Fusarium oxysporum f. sp melonis

Restriction enzyme-mediated integration (REMI) mutagenesis;was used to tag genes required for pathogenicity of Fusarium oxysporum f. sp, melonis, Of t he 1,129 REMI:transformants tested, 13 showed reduced pathogenicity on susc eptible melon cultivars, One of the mutants, FMMP95-1, was an arginine auxo troph, Structural analysis of the tagged site in FMMP95-1 identified a gene , designated ARG1, which possibly encodes argininosuccinate lyase, catalyzi ng the last step for arginine biosynthesis. Complementation of FMMP95-1 wit h the ARG1 gene caused a recovery in pathogenicity, indicating that arginin e auxotrophic mutation causes reduced pathogenicity in this pathogen.