1987 Volume 53 Issue 4 Pages 495-506
A mycelial disk of benomyl-resistant strain (IHES-3) of Botrytis cinerea was contactcultured in the center of colony of benomyl-sensitive strain (IPCR-1). Mycelial disks, which were collected from IPCR-1 colony contacted with IHES-3, were placed on PSA media containing benomyl. IPCR-1 mycelial disk (PH-1) which was 1cm distant from IHES-3 disk showed resistance to benomyl. Benomyl showed MIC of 1, 000ppm to PH-1 which was a medial value between MIC to IPCR-1 (<3ppm) and that to IHES-3 (>3, 000ppm).Colonies and hyphae of PH-1 were morphologically similar to those of IPCR-1, but the growth was more or less poor in contrast to IPCR-1. In hyphae of PH-1, nuclei which were similar to those of IHES-3 were found in addition to nuclei that resemble those of IPCR-1. Pathogenicity of PH-1 to cucumber showed nearly middle grades of the two strains. PH-1 was stable in the above properties, even though the subculture was repeated more than ten times on PSA media. Hyphal fusion was observed between hyphae of IPCR-1 and IHES-3 on PSA medium. Also, in conidial coculture of the two strains on glass slides hyphal fusions of 6 types were observed, and the frequency was about 2.5% between hyphae of IPCR-1 and IHES-3. The light microscopy showed transfer of nuclei between the two strains by hyphal fusion, but did not whether karyogamy was followed or not.