Abstract
Verticillium dahliae, a soilborne plant pathogen, causes wilt disease in various dicotyledonous plant species. The host range of V. dahliae differs among strains, but the system which determines the pathogenicity of each strain on a plant species remains unclear. An earlier study using a genetic cross between the strains Chr208 and Vdp4, which are respectively nonpathogenic and pathogenic on sweet pepper, revealed that the genomic region GL3 linked to pathogenicity. A similar result was obtained in this study by genetic crossing between the Chr208 (nonpathogenic) and Cns (pathogenic) strains. By contrast, the genomic region GL3 was not consistently linked with pathogenicity in the genetic cross between the strains TV103 (nonpathogenic) and Cns (pathogenic). Using DNA markers to analyze recombinants obtained in this genetic cross revealed that another genetic region GL5 is linked to pathogenicity. It is particularly interesting, however, that recombinants which inherited the GL3 region from the nonpathogenic strain TV103 were less virulent on sweet pepper. Moreover, in the genetic cross between the strains TV103 (nonpathogenic) and Vdp4 (pathogenic), recombinants that inherited either region of the GL3 or the GL5 from the nonpathogenic strain TV103 were nonpathogenic on sweet pepper. These results suggest that, in addition to the GL3, the GL5 region is involved in V. dahliae pathogenicity on sweet pepper.
