Species-specific PCRs differentiate Rosellinia necatrix from R. compacta as the prevalent cause of white root rot in Japan

Rosellinia compacta, described recently, resembles R. necatrix and also causes white root rot. Here a species-specific PCR was developed for R. compacta, and the two R. necatrix-specific primer sets already available were validated in terms of species specificity. PCRs using the primer sets for R. necatrix amplified specific products exclusively from R. necatrix isolates. The R. compacta-specific primer set exclusively detected R. compacta, which appears to be a rare but widely distributed species. We conclude that R. necatrix is the major cause of the disease in Japan but that the involvement of R. compacta should be studied further.